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How can we use technology to detect Black Holes

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Why are black hole such a significant matter to investigate when we don't know what each black hole contains

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The EHT (Event Horizon Telescope) is a remarkable piece of technology that has allowed humans to detect black holes

The EHT is not just one telescope, but it's a network of radio telescopes spread across the world

They are strategically placed in order to create an earth-sized telescope through a technique called VLBI(Very long baseline interferometry)

This technique allows the telescopes to function in unison, increasing their effectiveness with greater resolution

The EHT specializes in observing radio wavelengths. This is because the accretion disks around black holes emit radio waves

The main component of a radio telescope is the parabolic dish antenna

The shape is designed to focus incoming radio waves onto a receiver located at the focal point

The larger the dish, the more details it is capable of detecting

The data observed by each telescope is then collected and put together to form high-quality images.

The EHT made an astonishing discovery of a supermassive black hole in 2019 at the center of galaxy M87, it was the first direct visual detection of a black hole

Further question:

How can we figure out when a black hole is about to form?

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The Event Horizon Telescope is a global network of synchronized radio observatories that work in unison to observe radio sources associated with black holes with angular resolution comparable to their event horizons. The required extreme resolving power makes scientists and engineers go to some of the most extreme environments on the Earth to collect data.

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LIGO consists of two identical observatories, one located in Washington and one in Louisiana

Each of these observatories is spread by two identically long arms, in an L shape approximately 4 km in both directions

The main component of LIGO’s functionality is the use of laser light

This light is shot down each arm where it then meets a highly reflective mirror at the end and then continues to move throughout the structure

Black holes generate gravitational waves that cause stretching and compressions through spacetime

When these waves hit Earth, it changes the length that the light has to travel which is found by sensitive detectors.

These detectors are capable of measuring extremely small changes in length, even to a fraction of the diameter of a proton

To confirm the detection of a black hole, scientists at LIGO communicate with other scientists such as the ones at Virgo in Europe to ensure accuracy.

Further queston:

How do we figure out how far away the black hole is?

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LIGO stands for "Laser Interferometer Gravitational-wave Observatory". It is the world's largest gravitational wave observatory and a marvel of precision engineering. Comprising two enormous laser interferometers located 3000 kilometers apart, LIGO exploits the physical properties of light and of space itself to detect and understand the origins of gravitational waves (GW).

LIGO (and other detectors like it, e.g., Virgo, GEO, and KAGRA) is not an electromagnetic (EM) observatory and thus bears no resemblance to the kind of place most people probably think of when they hear the word "Observatory". Take the photo of the Palomar 200" Hale Telescope dome at right, for example. Instead, LIGO is configured as a very large L-shaped detector with 4km (2.5 mi) long arms, as shown in the aerial photo of LIGO's Livingston Louisiana detector below right.

LIGO is fundamentally different from electromagnetic observatories in three primary ways:
LIGO is blind
Unlike optical or radio telescopes, LIGO does not see electromagnetic radiation (e.g., visible light, radio waves, microwaves). But it doesn't have to because gravitational waves are part of the electromagnetic spectrum. They are a completely different phenomenon altogether (though in some cases, EM astronomers hope to see some form of light coming from GW sources, like that which occurred immediately following the binary neutron star merger detected in August 2017). In fact, electromagnetic radiation is so unimportant to LIGO that its detector components are completely isolated and sheltered from the outside world.
LIGO can't point to specific locations in space
Since LIGO doesn't need to collect light from stars or other objects or regions in space, it doesn't need to be round or dish-shaped like optical telescope mirrors or radio telescope dishes. Nor does it have to be steerable, i.e., able to move around to point in a specific direction. Instead, each LIGO detector consists of two 4 km (2.5 mi.) long, 1.2 m-wide steel vacuum tubes arranged in an "L" shape (LIGO's laser travels through these arms), and enclosed within a 10-foot wide, 12-foot tall concrete structure that protects the tubes from the environment.
It is difficult for a single LIGO detector to confirm a gravitational wave signal on its own
The initial discovery of gravitational waves required that the signal be seen in both detectors (Hanford and Livingston). Happily, GW150914 fulfilled that requirement and since then, dozens more signals have been observed by the two LIGO detectors, and some also by Italy's Virgo detector. But now that LIGO scientists better understand signal sources and how the instruments respond to gravitational waves, in some cases, a detection can be made with one instrument. However, to help electromagnetic astronomers find a possible light source associated with a gravitational wave detection, multiple instruments - ideally 3 or more - must be able to detect the signal to localize the source on the sky (in a process similar how a cellphonecan be located with three or more nearby cell towers). This was the case for the first-ever binary neutron star merger detection, GW170817.

Though LIGO's mission is to detect gravitational waves from some of the most violent and energetic processes in the Universe, the data LIGO collects may also contribute to other areas of physics such as gravitation, relativity, cosmology, astrophysics, particle physics, and nuclear physics. In this way, LIGO is also a physics experiment on the scale and complexity of some of the world's giant particle accelerators and nuclear physics laboratories.

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A description of LIGO as a unique "observatory" dedicated to detecting gravitational waves and how it's different from a conventional observatory.

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Black holes are important to learn more about as it causes a scientific clash between the theory of general relativity and quantum theory when analyzing the singularity and the event horizon. It is the key to understanding the universe as it is an existing matter that forces researchers to look deeping into the fundamental properties of space and time.

Black holes begin to contradict scientists' basic knowledge of space and time when considering the center of a black hole, also called the singularity. Given Pernrose’s spacetime diagram of a black hole where time and space are not consistent throughout the black hole, scientists are able to deduce that the singularity is not an actual point and instead is a moment in time.

The event horizon surrounds the black hole and is a point in space where time has completely stopped. Given the glow and temperature emitted from the event horizon, Steven Hawking considered quantum theory and quantum mechanics which provided the idea that within the event horizon, a pair of particles known as the entangled particles are on either side of the event horizon. One at the edge of the black hole while the other is not. There is a chance that that particle escapes the event horizon which would mean that the black hole will eventually get smaller and smaller. This also means that black holes have a lifespan.

Once a black hole meets the end of its lifespan, all the matter sucked into the hole would have been broken down to particle form and escaped the event horizon. Given the law of conservation of information, there is theoretically a way for the objects that fell into the hole to be reconstructed. This is called the black hole information paradox as scientists originally believed that black holes erased information from the universe.

By delving deeper into understanding black holes, scientists will be able to have a more solid understanding of gravity, space, and time. They must first understand the fundamental concepts of physics in order to advance in physics research.

Next question: How were researchers able to observe black holes if light cannot escape? How was Penrose able to create the diagram of the inside of a black hole? How does this compare to other scientists?

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Brian Cox on how black holes could unlock the mysteries of our universe

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One piece of technology that can be used to detect black holes is called EHT(Event Horizon Telescope)

The EHT was originally created to be able to find and get a visible picture of Sagittarius A* the black hole in the center of the Milky Way approx 26,000 light years away.

EHT is made up of a combination of telescopes from US, Mexico, Chile, France, Greenland and the South Pole

Uses very long baseline interferometry (VBSI) to locate and show a black hole

VBSI

a network made up of radios on the ground and in space, that uses all radio wavelengths together to act as one telescope

VBSI does not work like a normal telescope, they first start by freezing the light, capture it, then record this and then send the data back to their supercomputer, where finally this supercomputer will take all the data that was just sent in from each telescope and compares them to make a final picture

To be able to combine all the radios together they need some way to keep  time to stay in sync to be able to multiply the telescopes together….. To do this they have been using atomic clocks that keep an accuracy of a trillionth per second

Scientists are trying to add on 64 radio dishes from the Atacama Large Millimeter from Chile, this will allow the EHT to be able to read higher frequencies, allowing the telescope's sensitivity to increase by a factor of 10 allowing us to have the resolution to be able to measure and view black holes.

next question :

How are scientists able to calculate the mass of a black hole?

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Black holes are essentially invisible, but astronomers are developing technology to image the immediate surroundings of these enigmas like never before. Within a few years, experts say, scientists may have the first-ever picture of the environment around a black hole, and could even spot the theorized "shadow" of a black hole itself.

Black holes are hard to see in detail because the large ones are all far away. The closest supermassive black hole is the one thought to inhabit the center of the Milky Way, called Sagittarius A* (pronounced "Sagittarius A-star"), which lies about 26,000 light-years away. This is the first target for an ambitious international project to image a black hole in greater detail than ever before, called the Event Horizon Telescope (EHT).

The EHT will combine observations from telescopes all over the world, including facilities in the United States, Mexico, Chile, France, Greenland and the South Pole, into one virtual image with a resolution equal to what would be achieved by a single telescope the size of the distance between the separated facilities. [The Strangest Black Holes in the Universe]

"This is really an unprecedented, unique experiment," said EHT team member Jason Dexter, an astrophysical theorist at the University of California, Berkeley. "It's going to give us more direct information than we've ever had to understand what happens extremely close to black holes. It's very exciting, and this project is really going to come of age and start delivering amazing results in the next few years."

From Earth, Sagittarius A* looks about as big as a grapefruit would on the moon. When the Event Horizon Telescope is fully realized, it should be able to resolve details about the size of a golf ball on the moon. That's close enough to see the light emitted by gas as it spirals in toward its doom inside the black hole.

Very long baseline interferometry
To accomplish such fine resolution, the project takes advantage of a technique called very long baseline interferometry (VLBI). In VLBI, a supercomputer acts as a giant telescope lens, in effect.

"If you have telescopes around the world you can make a virtual Earth-sized telescope," said Shep Doeleman, an astronomer at MIT's Haystack Observatory in Massachusetts who's leading the Event Horizon Telescope project. "In a typical telescope, light bounces off a precisely curved surface and all the light gets focused into a focal plane. The way VLBI works is, we have to freeze the light, capture it, record it perfectly faithfully on the recording system, then shift the data back to a central supercomputer, which compares the light from California and Hawaii and the other locations, and synthesizes it. The lens becomes a supercomputer here at MIT."

A major improvement to the Event Horizon Telescope's imaging ability will come when the 64 radio dishes of the ALMA (Atacama Large Millimeter/submillimeter Array) observatory in Chile join the project in the next few years.

"It's going to increase the sensitivity of the Event Horizon Telescope by a factor of 10," Doeleman said. "Whenever you change something by an order of magnitude, wonderful things happen." [Photos: ALMA Inaugurated in Chile]

Very long baseline interferometry has been used for about 50 years, but never before at such a high frequency, or short wavelength, of light. This short-wavelength light is what's needed to achieve the angular resolution required to measure and image black holes.

Grand technical challenge
Pulling off the Event Horizon Telescope has been a grand technical challenge on many fronts.

To coordinate the observations of so many telescopes spread out around the world, scientists have needed to harness specialized computing algorithms, not to mention powerful supercomputers. Plus, to accommodate the time difference between the various stations, extremely accurate clocks are needed.

"We had to prove you could keep time well enough at all the stations, and that the detectors at all the telescopes were good enough, that when you multiply the two signals from two telescopes you wouldn't get just noise," said Dan Marrone, an astronomer at the University of Arizona's Steward Observatory who's building a receiver to enable the South Pole Telescope to join the project. [No Escape: Dive Into a Black Hole (Infographic)]

The researchers have been using atomic clocks made of what's called hydrogen masers to keep time to an accuracy of about a trillionth of a second per second.

"We use this property of the structure of the hydrogen atom to create a fundamental time reference for us that transitions between two states of the electron in a hydrogen atom," Marrone said. "It creates a low-frequency signal that through careful design you can make a very precise oscillator. It creates very perfect oscillations for a short time period. That means we can average our data over those time periods because they will all have kept time very perfectly."

Testing general relativity
With the unprecedented data soon to be collected by the Event Horizon Telescope, scientists are hoping to better understand the strange physics of black holes, which are some of the most extreme, bizarre objects in the universe.

The black hole at the center of the Milky Way is thought to contain the mass of about 4 million suns, all packed into an incomprehensibly small area. The ultra-strong densities there should produce some very extreme gravitational forces that offer a rare test of Einstein's general theory of relativity.

"The Event Horizon Telescope is going to look at emission at the edge of the black hole itself," Doeleman said. "That's an area where the gravity is so strong that light is bent and the structures you see are dominated by strong gravity, where you absolutely need Einstein to understand what you're seeing. It becomes a laboratory of extremes."

One question scientists hope to answer is whether black holes really have event horizons, as predicted by general relativity. An event horizon is a theorized boundary around a black hole that marks the "point of no return" where matter and even light can't escape. If event horizons exist, general relativity also predicts black holes will have shadows, or darkened regions where light has been swallowed. If black holes do produce shadows, the Event Horizon Telescope should be able to see one at Sagittarius A* within the next few years, said Dexter, the University of California, Berkeley, theorist.

"That would be the most extreme general relativistic effect detected so far," he added.

X-raying black holes
While the Event Horizon Telescope is observing black holes in radio wavelengths, the other frontier of black hole astronomy is in the X-ray regime.

The gas falling into black holes emits light across the electromagnetic spectrum, but the hottest, most energetic gas, which is swirling closest to a black hole's event horizon, can be seen in X-ray light.

This light is only visible beyond the atmosphere of Earth, to space telescopes such as NASA's Chandra observatory and NuSTAR telescope, Europe's XMM Newton observatory, and Japan's Suzaku telescope. These observations aren't directly imaging the environs of black holes, like the Event Horizon Telescope, but are breaking up X-ray light into its constituent colors, or wavelengths, to search for clues about what's happening to the gas in those extreme environments.

For example, astronomer Chris Reynolds of the University of Maryland, College Park, uses X-ray observations to study the spins of black holes. "Because the physics is so extreme, when a black hole spins, it actually twists up the space-time around it and we can see the effect it has on gas orbiting the black hole," Reynolds said.

And by studying black holes in various wavelengths, researchers hope to build up a more complete understanding of these strange cosmic objects.

"The gas, as it falls into a black hole, emits radio waves, which is what the Event Horizon Telescope is trying to see, and it also makes X-rays, and that gives you very complementary views on the properties of the infalling gas and the black hole," Reynolds said. "The Event Horizon Telescope is on the threshold of some extremely close results, and we're all looking forward to it."

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Incredible technology: How to see an invisible black hole

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Black holes are essentially invisible, but astronomers are developing technology to image the immediate surroundings of these enigmas like never before. Within a few years, experts say, scientists may have the first-ever picture of the environment around a black hole, and could even spot the theorized "shadow" of a black hole itself.

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What happens at the center of a Black Hole? 

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What happens at the center of a Black Hole? 

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1. Planck Stars:

Planck star is when instead of matter being infinitely compressed in a blackhole, there is a smallest possible configuration of matter instead.

In loop quantum gravity, space and time are quantized, meaning that they are composed of tiny chunks

“The theoretical chunkiness” of space and time prevents the formation of singularities inside black holes, which makes them temporary objects.

2. Gravastars:

Another theoretical concept to replace the singularity is called the gravastar

Unlike a black hole, a gravastar is filled with dark energy instead of having a singularity.

Dark energy causes space-time to expand outward, preventing matter from penetrating the event horizon of a gravastar

Recent observations of merging black holes with gravitational wave detectors have potentially ruled out the actual existence of gravastars.

3. Rotating Black Holes and Wormholes:

Real Black holes are not necessarily stationary and uncharged. Their rotation plays a significant role.

Rotation of a black hole can stretch the singularity into a ring

Passing through the ring singularity can theoretically lead to a wormhole, through which one might emerge from a white hole into a different part of the universe

Interior of black holes are considered unstable and the math needs improvement as well

4. Challenges and Uncertainties:

The article acknowledges that the existence of Planck Stars and Gravastars is in doubt and their reality is still not fully confirmed

The inside of rotating black holes, despite their theories, face difficulties, as their extreme conditions might lead to the destruction of the black hole itself.

Next questions:

Are there any ongoing experiments or observations that are trying to provide evidence for the existence of Planck Stars, Garavstars or the theoretical outcomes of rotating black holes?

If the theoretical concepts proposed by scientists were to be proven true, how might this reshape our understanding of the universe, space travel or even the nature of time and gravity?

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(Image credit: Shutterstock)

Paul M. Sutter is an astrophysicist at Stony Brook and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of . Sutter contributed this article to Space.com's Expert Voices: Op-Ed & Insights.

The singularity at the center of a is the ultimate no man's land: a place where matter is compressed down to an infinitely tiny point, and all conceptions of time and space completely break down. And it doesn't really exist. Something has to replace the singularity, but we're not exactly sure what.

Let's explore some possibilities.
Related: Black holes of the universe (images)
Planck stars

It could be that deep inside a black hole, matter doesn't get squished down to an infinitely tiny point. Instead, there could be a smallest possible configuration of matter, the tiniest possible pocket of volume.

This is called a Planck star, and it's a theoretical possibility envisioned by loop quantum gravity, which is itself a highly hypothetical proposal for creating a quantum version of gravity. In the world of loop quantum gravity, space and time are quantized - the universe around us is composed of tiny discrete chunks, but at such an incredibly tiny scale that our movements appear smooth and continuous.

This theoretical chunkiness of space-time provides two benefits. One, it takes the dream of quantum mechanics to its ultimate conclusion, explaining gravity in a natural way. And two, it makes it impossible for singularities to form inside black holes.

As matter squishes down under the immense gravitational weight of a collapsing star, it meets resistance. The discreteness of space-time prevents matter from reaching anything smaller than the Planck length (around 1.68 times 10^-35 meters). All the material that has ever fallen into the black hole gets compressed into a ball not much bigger than this. Perfectly microscopic, but definitely not infinitely tiny.

This resistance to continued compression eventually forces the material to un-collapse (i.e., explode), making black holes only temporary objects. But because of the extreme time dilation effects around black holes, from our perspective in the outside universe it takes billions, even trillions, of years before they go boom. So we're all set for now.

Related: What is gravity?

Gravastars

Another attempt to eradicate the singularity - one that doesn't rely on untested theories of quantum gravity - is known as the gravastar. It's such a theoretical concept that my spell checker didn't even recognize the word.

The difference between a black hole and a gravastar is that, instead of a singularity, the gravastar is filled with dark energy. Dark energy is a substance that permeates space-time, causing it to expand outward. It sounds like sci-fi, but it's real: dark energy is currently in operation in the larger cosmos, causing our entire universe to accelerate in its expansion.

As matter falls onto a gravastar, it isn't able to actually penetrate the event horizon (due to all that dark energy on the inside) and therefore just hangs out on the surface. But outside that surface, gravastars look and act like normal black holes. (A black hole's event horizon is its point of no return - the boundary beyond which nothing, not even light, can escape.)
The universe: Big Bang to now in 10 easy steps
However, recent observations of merging black holes with gravitational wave detectors have potentially ruled out the existence of gravastars, because merging gravastars will give a different signal than merging black holes, and outfits like LIGO (the Laser Interferometer Gravitational-Wave Observatory) and Virgo are getting more and more examples by the day. While gravastars aren't exactly a no-go in our universe, they are definitely on thin ice.

Let's go for a spin

Planck stars and gravastars may have awesome names, but the reality of their existence is in doubt. So maybe there's a more mundane explanation for singularities, one that's based on a more nuanced - and realistic - view of black holes in our universe.

The idea of a single point of infinite density comes from our conception of stationary, non-rotating, uncharged, rather boring black holes. Real black holes are much more interesting characters, especially when they spin.

The spin of a rotating black hole stretches the singularity into a ring. And according to the math of Einstein's theory of general relativity (which is the only math we've got), once you pass through the ring singularity, you enter a wormhole and pop out through a white hole (the polar opposite of a black hole, where nothing can enter and matter rushes out at the speed of light) into an entirely new and exciting patch of the universe.

One challenge: the interiors of rotating black holes are catastrophically unstable. And this is according to the very same math that leads to the prediction of the traveling-to-a-new-universe stuff.

The problem with rotating black holes is that, well, they rotate. The singularity, stretched into a ring, is rotating at such a fantastic pace that it has incredible centrifugal force. And in general relativity, strong enough centrifugal forces act like antigravity: they push, not pull.

This creates a boundary inside the black hole, called the inner horizon. Outside this region, radiation is falling inward toward the singularity, compelled by the extreme gravitational pull. But radiation is pushed by the antigravity near the ring singularity, and the turning point is the inner horizon. If you were to encounter the inner horizon, you would face a wall of infinitely energetic radiation - the entire past history of the universe, blasted into your face in less than a blink of an eye.

The formation of an inner horizon sows the seeds for the destruction of the black hole. But rotating black holes certainly exist in our universe, so that tells us that our math is wrong and something funky is going on.

What's really happening inside a black hole? We don't know - and the scary part is that we may never know.

Additional resources

You can learn more about black holes at this NASA explainer page. This BBC Earth piece has good basic information about black holes as well, and it also describes what would happen to you if you fell into one of these light-gobbling monsters. And the Stanford Encyclopedia of Philosophy has a good, detailed breakdown of black holes and singularities.

Rovelli, C. and Vidotto, F, 2014. "Planck stars," International Journal of Modern Physics D, Vol. 23, No. 12. https://doi.org/10.1142/S0218271814420267

Sakai, N. et al, 2014. "Gravastar shadows," Physical Review D, Vol. 90. https://journals.aps.org/prd/abstract/10.1103/PhysRevD.90.104013

Taylor, E. and Wheeler, J. "Exploring Black Holes: Introduction to General Relativity." Addison Wesley Longman, 2000. https://www.amazon.com/Exploring-Black-Holes-Introduction-Relativity/dp/020138423X

Editor's note: Learn more by listening to the episode What really happens at the center of a black hole? on the Ask A Spaceman podcast, available on and on the Web at http://www.askaspaceman.com. Thanks to Andy P., Brittany, Jeff J., Robert S., Vladimir B., Jack S., @Grobillard, and James L. for the questions that led to this piece! Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutter and facebook.com/PaulMattSutter. This story was first published on Oct. 27, 2020. It was updated and republished on Feb. 8, 2022.
Bibliography

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What happens at the center of a black hole?

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(Image credit: Shutterstock) Paul M. Sutter is an astrophysicist at Stony Brook and the Flatiron Institute, host of Ask a Spaceman and Space Radio , and author of . Sutter contributed this article to Space.com's Expert Voices: Op-Ed & Insights.

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Black holes are made of matter packed so tightly that gravity overwhelms all other forces

Black hole are so extreme that they are the perfect place to test the limits of the rules of the universe

Observing black holes allow us to better understand the nature of the universe

We used the collisions of black hole to prove Einstein's theories about

Black holes also have some distinct role to play in the formation of galaxies, including our own

Black holes can help us understand a wide variety of topics including:

Understanding extreme physic and how stars and planets grow

Some supermassive are active engine to easily swallow starts and through that spiraling electromagnetic field, super-heated gasses and materials known as Quasars are flung out

This process can also tell us about the physics of these extreme environments, along with showing us the conditions under which galaxies, planets and stars are born grow and die

Understand how fast the universe is expands, linking back to how it initially evolved

Holz and other scientists have used the collision of black holes to calculate how fast the universe is expanding, finding the Hubble constant

The Hubble constant allows us to understand the past present and future behavior of the universe and the nature of dark matter and energy

Reconciling our major theories of the universe

Black holes allow us to see the link between quantum mechanics and general reality, the laws for the smallest particles and the largest respectively

Stephen Hawking theories that the laws of quantum mechanics suggest that black holes have a very tiny temperature, implying that some radiation is leaving the black hole which can further imply the loss of mass faster and faster over time until they inevitably explode, even if it takes trillions and trillions of years to happen

Next questions

What other practical applications of black holes are there? What else can they prove?

How rare are they? Has the number increased? Are they more or less concentrated in certain areas? What affects the concentration?

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What is a black hole, really? What do they look like, eat, and how do they grow? What's inside a black hole? Learn the answers to these questions and more.

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How can we research Black holes since they don't emmit light?

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How can we research Black holes since they don't emmit light?

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Scientists can’t directly observe black holes with telescopes that detect x-rays, light or any other forms of electromagnetic radiation

Whereas we can infer the presence and location based on the effect of the black hole on the matter around them

Ex. If a black hole passes through a cloud of interstellar matter it will  draw in into itself in a process known as accretion

If this same scenario where to happen with a star, it would break apart and prduce heat as it accelerates toward the hole, emitting x-rays that radiate into space

Next questions

Can the heat that is emitted help us predict the size of the black hole? Does the acceleration vary?

What if we can’t see how much is absorbed by the hole?

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Don't let the name fool you: a black hole is anything but empty space. Rather, it is a great amount of matter packed into a very small area - think of a star ten times more massive than the Sun squeezed into a sphere approximately the diameter of New York City.

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How are scientists able to calculate the mass of black holes.

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How are scientists able to calculate the mass of black holes.

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Black holes

Black holes do not radiate or reflect light so supermassive black holes cannot be seen

Although when the gravitational force of the black holes starts to pull dust and gas inside of it, that light will then heat up and start radiating while being pulled inside making the black hole “visible”

Black holes are made of three properties; mass, spin and charge

Quasars

Celestial objects

Emits an extraordinary amount of energy

Kind of looks like a star through a telescope

Suggested that they contain black holes(reason why scientists are searching through them to potentially calculate mass of black holes)

Potentially could represent the evolution stages of an upcoming galaxy

Reverberation mapping

Technique that allows scientists to measure the mass of black holes

First they compare the brightness of the gas near the black hole (also known as the continuum region). This gas affects the gasses that are farther away from the continuum region, but since light takes time to travel there is a delay between the continuum region and the affected outer region. They will measure the delay to show how far apart the outer gas disk is from the black hole. Finally they add the rotation rate around the galaxy to then find the mass of the black hole.

Not very time efficient

Scientist say that it is painfully slow

Takes about 5 months to calculate and observe the Reverberation effect

Over the past 20 years scientist have only been able to calculate the mass of 60 black holes in nearby galaxies

Reverberation project

Objective is to find a way to calculate the mass of supermassive black holes faster

New technology used: the wide view telescope located at the Apache Point Observatory in Sunspot New Mexico

The telescope provides them with more data at a faster pace, leading to them finishing their calculations faster

With help of the new technology they plan to measure the masses of supermassive black holes in more than 1000 quasars

Further question:

How do quasars affect the evolution of galaxies?

What influences do quasars have on galaxies?

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How Astronomers Are Measuring Monster Black Hole Masses Faster Than Ever Before

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A new, ultrafast method of measuring the mass of massive black holes in distant galaxies could help scientists better understand how these monsters influence the lives of galaxies.

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It is very hard to accurately detect the distance of black hole but there are some strategies used by scientists over time.

In 2009, scientists accurately detected the distance of earth from a black hole using a parallax technique. A small group of researchers used information from the High Sensitivity Array to triangulate the distance to the black hole V404 Cyg. This technique has around a 50% chance of error as not all black holes have the same characteristics and qualities.

By looking for material and stuff that falls into a black hole, scientists are able to deduce that there is a black hole in that area. When being sucked into a black hole, the matter being consumed illuminates and rises in temperature which can be observed. This random occurrence for the material in space signifies something aggressively pulling that material towards them which can only be explained by black holes. We are able to deduct how far a material is from Earth as long as we can see it.

By also observing the stars and matter around “empty” space, it may signify that there is a black hole. Due to a black hole’s gravitational pull, stars and other materials would orbit around it. To researchers collecting data, they would see these stars orbiting around what seems to be nothing. This would indicate a black hole is present.

Another way to detect black holes is to detect the gravitational ripples when they collide. From the signal of two black holes colliding, we are able to detect how large the holes were, how far away they were before colliding, and how fast they were traveling.

Scientists have also found a way to detect their distance and presence using X-rays emitted from black holes. Researchers take the distance of an accompanying star of the black hole, also called a companion star. This results in lower percent error as they are close together as long as it is not in our galaxy. The companion star as it circles into the black hole can emit strong X-rays which can be detected from earth. Similarly, there are black holes called the “transient black holes” that occasionally release large amounts of X-ray bursts which can also be detected by technology on Earth. Though this is rare which is why it is called the “transient” black hole.

https://medium.com/@lyndiechiou/how-to-estimate-the-distance-to-a-black-hole-when-you-cant-parallax-it-c4270c638b10

Next questions: What is the result of two black holes colliding? How are they able to collide? Does this help researchers determine the mass, distance, and speed? What do the reactions of the black holes say about their characteristics?

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Scientists at the time were shocked and skeptical. The most famous astrophysicist at the time, Arthur Eddington, publicly trashed the idea at a gathering, saying, "I think there should be a law of nature to prevent a star from behaving in this absurd way!"

However, the damage was done. "Once the astrophysics community had come to grips with a calculation performed by a 19-year-old student sailing off to graduate school, the heavens could never again be seen as a perfect and tranquil dominion," physicist Freeman Dyson later wrote.

Scientists soon worked out that other laws, including Einstein's theory of general relativity, required black holes to exist.

The idea became increasingly accepted. In the latter half of the 20th century, eminent theoretical scientists, including Steven Hawking at Cambridge, John Wheeler and Jacob Bekenstein at Princeton, Chandrasekhar and Robert Wald at the University of Chicago, and many others, explored the details of the mathematics and physics behind black holes.

Meanwhile, evidence from telescopes began to pile up that black holes were out there in the universe.

In the 1960s, quasars were discovered-faraway objects that were emitting such strong radiation that there was no explanation other than gigantic black holes chewing up and spitting out matter.

Throughout the 1990s, scientists including Andrea Ghez and Reinhard Genzel precisely tracked the movements of stars around the center of our galaxy, proving they were orbiting around something invisible but so massive that it had to be a black hole. (They would receive the Nobel Prize in 2020 for this work.)

Then, in 2015, two special detectors known as the Laser Interferometer Gravitational-Wave Observatory (LIGO) picked up the ripples from a pair of black holes colliding. ( This also received a Nobel Prize, in 2018). They have since detected nearly 100 such collisions.

In 2019, the Event Horizon Telescope, a collection of telescopes around the world acting in concert, was able to take an image of the gas swirling around a gigantic black hole in another galaxy. They followed this in 2022 with an image of our "own" black hole-the one that sits in the center of the Milky Way. We are making more discoveries all the time!

What do black holes tell us about the universe?

Black holes are kind of like a playground for physicists. "They are literally made out of space and time," said Prof. Holz. Because they are so extreme, they are the perfect place to test the limits of the rules of the universe.

Observing them and thinking about their properties have yielded enormous insights about the nature of the universe. For example, detecting their collisions allowed us to test Einstein's theories about how mass, space, and time are related (as well as lots of other theories about the universe). Black holes also seem to play a role in the formation of galaxies; it's likely our supermassive black hole has something to do with how we came to be here today.

Some other things we can learn about the universe include:

Understanding extreme physics and how stars and planets grow. Some supermassive black holes are extremely active, gobbling up stars amid swirling magnetic fields and flinging out jets of superheated gas and material; these systems are known as quasars. Watching this process can tell us about the physics of these extreme environments. It can also tell us about the conditions under which stars, planets, and galaxies are born, grow, and die.

Understanding how fast the universe is expanding and therefore how it evolved. As we get more and more data on pairs of black holes colliding, Holz and others have worked out methods to use them to calculate how fast the universe is expanding. This number, called the Hubble Constant, is key to understanding the past, present, and future behavior of the universe, as well as the nature of dark matter and dark energy.

Reconciling our major theories of the universe.One of the most fundamental questions in modern physics is how to reconcile quantum mechanics, which is the law for the very smallest particles in the universe, with general relativity, which is the law for the very biggest things in the universe. These two sets of laws don't quite match up. But black holes are the perfect place to explore the links between them.

For example, Stephen Hawking theorized that the laws of quantum mechanics suggest that black holes have a very tiny temperature-which was surprising to scientists, since that implies some radiation is leaving the black hole. This has all sorts of implications for our understanding of physics. (One such implication: Black holes should eventually lose mass faster and faster over time until they explode. However, that will take trillions upon trillions of years to happen, so none of us will be around when it does.)

How was the first picture of a black hole taken?

In 2019, people around the world were thrilled to see the first image ever taken of a black hole-and then, in 2022, an image of our "personal" supermassive black hole in the Milky Way. The bright ring around each one is created by material glowing very hot as it circles the black hole.

This was the first direct image of a black hole ever taken-all of the other pictures you've seen are simulations or artist illustrations.

These black holes are so far away that no normal telescope would ever be powerful enough to see them. You would need a telescope the size of the Earth-but scientists figured out that they could piece together images taken simultaneously from telescopes situated all around the Earth instead. ( One of these was the South Pole Telescope, run by a collaboration headed by the University of Chicago, which provided the view from the bottom of the Earth.)

All together, this network of combined telescopes is referred to as the Event Horizon Telescope. They next hope to create a "movie" of the glowing gas moving around a black hole as it's pulled in. Learn more about the quest to take the images here.

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What is a black hole, really? What do they look like, eat, and how do they grow? What's inside a black hole? Learn the answers to these questions and more.

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How can we figure out when a black hole is about to form. 

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How can we figure out when a black hole is about to form. 

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The process of black hole formation begins when a star of an extremely large mass uses up its entire fuel supply and experiences a sudden loss of mass, causing the star to undergo a supernova. This results in the outer shell of the star being shed, leaving behind a remnant neutron star.

This shedding causes electrons to rapidly reattach themselves to hydrogen ions that have been cast off of the star, this attachment causes bright flareups to occur around the star. Once this attachment ceases, the remnant begins to cool and the light begins to phase, at the same time the particles begin to condense, causing the remnant neutron star to turn into a black hole.

A supernova is usually a key step in the process of black hole formation but in recent years it has been noted that a supernova is not a necessity in the formation of a black hole, even stars that fail to achieve a supernova can still end up as a black hole.

A research team conducting an experiment at Ohio State University, in Columbus was able to view the formation of a black hole. The team was led by Astronomy professor Christopher Kochanek.

The experiment involved observing a red supergiant star named N6946-BH1 and noting observations on it, this was done using images taken by the Hubble Space Telescope, and the Large Binocular Telescope.

The process described above is exactly what the team observing the star believed happened to it. During their observation, they were able to note that between 2009 and 2015, the star lost a significant amount of light without having undergone any changes to make it lose said light, this light was lost until the point where they could not view the star on the visible wavelength anymore.

It was only after this observation that they began to look into it further, eventually finding in 2009 the star had an extremely brief but intense flareup before beginning its slow descent into darkness. They now believe the star underwent a failed supernova causing it to begin the process of turning into a black hole with only the slightest and insignificant sign it had begun doing so.

This discovery provides more than one interesting conclusion, as not only does it provide another method in which black holes can potentially be covertly formed, but it also is the first time we were able to view the entire process of a black hole being formed.

Further Question:

What applications would gravitational waves provide in terms of exploring the universe?

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Artist's drawing a black hole (Cygnus X-1) as it pulls matter from a blue star beside it. Credit: NASA/CXC/M.Weiss

For almost half a century, scientists have subscribed to the theory that when a star comes to the end of its life-cycle, it will undergo a gravitational collapse. At this point, assuming enough mass is present, this collapse will trigger the formation of a black hole. Knowing when and how a black hole will form has long been something astronomers have sought out.

And why not? Being able to witness the formation of black hole would not only be an amazing event, it would also lead to a treasure trove of scientific discoveries. And according to a recent study by a team of researchers from Ohio State University in Columbus, we may have finally done just that.

The research team was led by Christopher Kochanek, a Professor of Astronomy and an Eminent Scholar at Ohio State. Using images taken by the Large Binocular Telescope (LBT) and Hubble Space Telescope (HST), he and his colleagues conducted a series of observations of a red supergiant star named N6946-BH1.

To break the formation process of black holes down, according to our current understanding of the life cycles of stars, a black hole forms after a very high-mass star experiences a supernova. This begins when the star has exhausted its supply of fuel and then undergoes a sudden loss of mass, where the outer shell of the star is shed, leaving behind a remnant neutron star.

This is then followed by electrons reattaching themselves to hydrogen ions that have been cast off, which causes a bright flareup to occur. When the hydrogen fusing stops, the stellar remnant begins to cool and fade; and eventually the rest of the material condenses to form a black hole.

Artist's impression of the star in its multi-million year long and previously unobservable phase as a large, red supergiant. Credit: CAASTRO / Mats Björklund (Magipics)

However, in recent years, several astronomers have speculated that in some cases, stars will experience a failed supernova. In this scenario, a very high-mass star ends its life cycle by turning into a black hole without the usual massive burst of energy happening beforehand.

As the Ohio team noted in their study - titled " The search for failed supernovae with the Large Binocular Telescope: confirmation of a disappearing star" - this may be what happened to N6946-BH1, a red supergiant that has 25 times the mass of the sun located 20 million light-years from Earth.

Using information obtained with the LBT, the team noted that N6946-BH1 showed some interesting changes in its luminosity between 2009 and 2015 - when two separates observations were made. In the 2009 images, N6946-BH1 appears as a bright, isolated star. This was consistent with archival data taken by the HST back in 2007.

However, data obtained by the LBT in 2015 showed that the star was no longer apparent in the visible wavelength, which was also confirmed by Hubble data from the same year. LBT data also showed that for several months during 2009, the star experienced a brief but intense flare-up, where it became a million times brighter than the sun, and then steadily faded away.

They also consulted data from the Palomar Transit Factory (PTF) survey for comparison, as well as observations made by Ron Arbour (a British amateur astronomer and supernova-hunter). In both cases, the observations showed evidence of a flare during a brief period in 2009 followed by a steady fade.

Artistic representation of the material around the supernova 1987A. Credit: ESO/L.

In the end, this information was all consistent with the failed supernovae-black hole model. As Prof. Kochanek, the lead author of the group's paper - - told Universe Today via email:

"In the failed supernova/black hole formation picture of this event, the transient is driven by the failed supernova. The star we see before the event is a red supergiant-so you have a compact core (size of ~earth) out the hydrogen burning shell, and then a huge, puffy extended envelope of mostly hydrogen that might extend out to the scale of Jupiter's orbit. This envelope is very weakly bound to the star. When the core of the star collapses, the gravitational mass drops by a few tenths of the mass of the sun because of the energy carried away by neutrinos. This drop in the gravity of the star is enough to send a weak shock wave through the puffy envelope that sends it drifting away. This produces a cool, low-luminosity (compared to a supernova, about a million times the luminosity of the sun) transient that lasts about a year and is powered by the energy of recombination. All the atoms in the puffy envelope were ionized-electrons not bound to atoms-as the ejected envelope expands and cools, the electrons all become bound to the atoms again, which releases the energy to power the transient. What we see in the data is consistent with this picture."

Naturally, the team considered all available possibilities to explain the sudden "disappearance" of the star. This included the possibility that the star was shrouded in so much dust that its optical/UV light was being absorbed and re-emitted. But as they found, this did not accord with their observations.

"The gist is that no models using dust to hide the star really work, so it would seem that whatever is there now has to be much less luminous then that pre-existing star." Kochanek explained. "Within the context of the failed supernova model, the residual light is consistent with the late time decay of emission from material accreting onto the newly formed black hole."

Naturally, further observations will be needed before we can know whether or not this was the case. This would most likely involve IR and X-ray missions, such as the Spitzer Space Telescope and the Chandra X-ray Observatory, or one of he many next-generation space telescopes to be deployed in the coming years.

The Large Binocular Telescope, showing the two imaging mirrors. Credit: NASA

In addition, Kochanek and his colleagues hope to continue monitoring the possible black hole using the LBT, and by re-visiting the object with the HST in about a year from now. "If it is true, we should continue to see the object fade away with time," he said.

Needless to say, if true, this discovery would be an unprecedented event in the history of astronomy. And the news has certainly garnered its share of excitement from the scientific community. As Avi Loeb - a professor of astronomy at Harvard University - expressed to Universe Today via email:

"The announcement on the potential discovery of a star that collapsed to make a black hole is very interesting. If true, it will be the first direct view of the delivery room of a black hole. The picture is somewhat messy (like any delivery room), with uncertainties about the properties of the baby that was delivered. The way to confirm that a black hole was born is to detect X-rays.

"We know that stellar-mass black holes exist, most recently thanks to the discovery of gravitational waves from their coalescence by the LIGO team. Almost eighty years ago Robert Oppenheimer and collaborators predicted that massive stars may collapse to black holes. Now we might have the first direct evidence that the process actually happens in nature.

But of course, we must remind ourselves that given its distance, what we could be witnessing with N6946-BH1 happened 20 million years ago. So from the perspective of this potential black hole, its formation is old news. But to us, it could be one of the most groundbreaking observations in the history of astronomy.

Much like space and time, significance is relative to the observer!

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Have we really just seen the birth of a black hole?

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For almost half a century, scientists have subscribed to the theory that when a star comes to the end of its life-cycle, it will undergo a gravitational collapse. At this point, assuming enough mass is present, this collapse will trigger the formation of a black hole.

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What influences do quasars have on galaxies.

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What influences do quasars have on galaxies.

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It is a common belief amongst Astronomers that the energy emitted from quasars has a limiting effect on the growth of galaxies.

One potential reason for this is that quasars create very intense and destructive winds that emit the equivalent energy of hundreds of solar masses each year. These winds sweep across their given galaxy, violently carrying away material needed to form new celestial bodies, this would in turn cause star birth to cease in the process, thereby limiting the growth of any given galaxy.

In order to properly assess whether or not the theory on these violent winds is true, NASA plans to use three-dimensional imaging spectroscopy, a function of the James Webb Telescope to draw relevant information on precisely how these quasar winds affect the galaxy they belong to.

For this experiment, NASA has selected three very bright quasars for two reasons.

First, these three quasars are noted to be some of the brightest known quasars at their respective distances.

Second, these three quasars have been confirmed to possess an outflow of material.

The final theory currently believed before anything can be confirmed, as this is the experiment that will hopefully provide a conclusive answer to the question, is that the outflow from powerful quasars prevents a galaxy from creating new stars and therefore growing the galaxy.

Further Question:

What happens to objects that are absorbed into a black hole?

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Supermassive black holes, which likely reside at the centers of virtually all galaxies, are unimaginably dense, compact regions of space from which nothing - not even light - can escape. As such a black hole, weighing in at millions or billions of times the mass of the Sun, devours material, it is surrounded by a swirling disk of gas. When gas from this disk falls towards the black hole, it releases a tremendous amount of energy. This energy creates a brilliant and powerful galactic core called a quasar, whose light can greatly outshine its host galaxy.

Astronomers widely believe that the energy from quasars is responsible for limiting the growth of massive galaxies. Shortly after the launch of NASA's James Webb Space Telescope, scientists plan to study the effect of three carefully selected quasars on their host galaxies in a program called Q3D.

A supermassive black hole is very small compared to its host galaxy - it's the equivalent of a penny in relation to the size of the entire Moon. Still, supermassive black holes have an immense influence on the galaxies they inhabit.

"Physically very small objects, supermassive black holes seem to have an enormous impact on the evolution of galaxies and eventually on the way our universe looks today," said Q3D principal investigator Dominika Wylezalek, a Research Group Leader at the University of Heidelberg in Germany.

Two decades ago, scientists hypothesized the critical role of quasars in limiting galaxy growth, but specific observational evidence has been surprisingly hard to come by. Scientists think a quasar's torrential winds push out the equivalent of hundreds of solar masses of material each year. As the quasar winds sweep across the galaxy's disk, material that otherwise would have formed new stars is violently carried away from the galaxy, causing star birth to cease. But observing the power and reach of quasars on their host galaxies remains a major unresolved issue in modern astrophysics. The Webb telescope could change that.
Analyzing Data in 3D
In addition to its exquisite sensitivity, resolution and infrared vision, Webb's capabilities include unique three-dimensional imaging spectroscopy. This special observing technique allows the team to get detailed measurements of light for every single pixel across the field of view. It stitches together many images at slightly different wavelengths. This allows scientists to spatially map gas motions inside the galaxy. The technique will revolutionize the understanding of the relationship between supermassive black holes and their host galaxies by allowing scientists to probe the stars, gas and dust in nearby and distant galaxies.

"Imaging spectroscopy is important for us because the winds in these distant quasars are not necessarily symmetric," explained co-principal investigator Sylvain Veilleux, a professor of astronomy at the University of Maryland, College Park. "So, one needs a spectrum at every position to determine what is their geometry and be able to draw the important information from these winds and the impact they have on their host galaxies."
Studying Three Quasars and Their Hosts
The Q3D team will study three bright quasars to measure the activity that comes from accreting material onto supermassive black holes, and how the host galaxies are affected by that activity. The team chose the three quasars for scientific reasons, but also to test and assess the capabilities of Webb. The objects intentionally span a very broad range of distance from Earth, from relatively nearby to very far away. They are also among the most luminous quasars at their respective distances and are known to have outflows of material.

Powerful quasar outflows appear to prevent a galaxy's gas from forming new stars and growing the galaxy. Scientists think this quasar-galaxy connection is crucial in determining how galaxies evolve from the early universe to today. It's especially important for galaxies a few times larger than the Milky Way, because quasar hosts are generally more massive galaxies.
Seeing Beyond the Bright Light
Quasars are very bright compared with the material around them, so the team is developing special software tools that allow them to study the phenomena. When quasars were discovered in the 1950s, they were brilliant radio sources that looked like stars on photographic plates, so they were called "quasi-stellar radio sources." Eventually, astronomers learned that quasars were actually inside of galaxies, but they were so bright that they outshone their host galaxies.

"We're interested in the quasar itself - the bright, star-like thing in the middle - but we're also interested in the fainter host galaxy. And not just the host galaxy, but the even fainter outflow from the host. This is the gas that's not circling around the quasar, or the center of the galaxy, but is instead flowing out. To see this really faint stuff behind the quasar, we have to remove the quasar's light. That's one unique thing the software will do." said co-investigator David Rupke, associate professor of physics at Rhodes College in Memphis, Tennessee. Rupke is leading the effort to write the software to analyze the Q3D data.
Paving the Way for Future Webb Studies
The Q3D study is part of the Director's Discretionary-Early Release Science program, which provides public data to the entire scientific community early in the telescope's mission. This program allows the astronomical community to quickly learn how best to use Webb's capabilities, while also yielding robust science.

"From a technical standpoint, with our observations, we are testing different modes, filters and combinations," explained Wylezalek. "It will be very useful for the scientific community to see the performance in these different modes. Scientifically, we are probing quasars at different luminosities and cosmic times to inform the community about Webb's performance when assessing different scientific questions."

The Q3D software will not only be useful for users observing quasars but for anyone observing bright, point-like, central sources on top of fainter sources. Such observations could include super star clusters, supernovas, tidal disruption events, or gamma-ray bursts.

The James Webb Space Telescope will be the world's premier space science observatory when it launches in 2021. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

For more information about Webb, visit www.nasa.gov/webb.
By Ann Jenkins
Space Telescope Science Institute, Baltimore, Md.

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NASA's Webb to Study Quasars and Their Host Galaxies in Three Dimensions - NASA

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Supermassive black holes, which likely reside at the centers of virtually all galaxies, are unimaginably dense, compact regions of space from which nothing -

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What happens to objects that are absorbed into a black hole?

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What happens to objects that are absorbed into a black hole?

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With enough mass, gravitational attraction within the matter itself overcomes all other forces and matter beings to collapse

Then the matter itself keeps collapsing until it reaches singularity, becoming infinitely dense and is infinitely small

At this point, space-time starts to distort, then nothing can escape from the immediate region, not even light

Karl Schwarzschild derived an equation for the radius of a black hole also known as an event horizon

Even though the center is simply a singularity, we say that it is a black hole, the size of the event horizon around it

Once inside the black holes event horizon, the matter being absorbed will be torn apart into its smallest subatomic components and eventually be squeezed into the singularity

Once the singularity accumulates more and more matter, the size of the black hole’s event horizons gets larger and larger

Most believed that the matter in a black hole once consumed would be forever gone, whereas Steven Hawking believe that black holes could radiate energy away known as hawking radiation

The black holes eventually start to lose what they absorbed very slowly

This process is so incalculably slow that even if a small black hole was to go through this process is would take an unimaginably long time

Next Questions

Is there  a “Max capacity” to just how much a single black hole can consume before ending?

How does the amount of matter the black hole consumes affect its lifespan?

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Where does the matter go when it is pulled into a black hole?

August 2001

Isacc Newton determined in the late 1600's that the force of gravity was due to matter or more specifically mass. The force of gravity is created by mass and gravity always attracts other mass. Newton's theories first appeared in his famous book, "The Principia." In the 1700's scientists speculated on the existence of massive objects with tremendous gravitational forces which today we call black holes. However it was not until Einstein published his theory of general relativity in 1915 that the black hole theory really received wide attention.

Relativity showed that gravity is related to the curvature of space and that a black hole is a place where the curvature becomes so extreme that a "hole" forms. Imagine a waterbed with a flat surface. Now place a bowling ball on it, the surface is distorted or bent. With a lot of mass, say a lead bowling ball, a "hole" forms on the surface of the bed. Similarly, a mass distorts or bends space. To form a black hole, a lot of matter is needed and must be concentrated in a small amount of space.

With sufficient mass, gravitational attraction within the matter itself overcomes all other forces and matter begins to collapse. The matter continues to collapse to a point that is known as a singularity. This point has infinite mass and density and is infinitely small. The effect of this point on space-time is to distort it so that nothing can escape from the immediate region, not even light. Since no light can escape we say the region is black hence the name black hole. Near singularities the known laws of physics break down. For this reason considerable time and effort is being spent studying this strange phenomena.

In 1916, German astrophysicist Karl Schwarzschild derived an equation for the radius of a black hole. This Schwarzschild radius, also called the event horizon, is proportional to the mass of the black hole, M, and may be written as Rs = (1.48 x 10-27) times M. This radius is the point or distance from the singularity at which light can still escape from the region. At a distance less than the event horizon radius, everything disappears. Although the matter at the center is really a singularity, we say it is a black hole the size of the event horizon distance.

When matter falls into or comes closer than the event horizon of a black hole, it becomes isolated from the rest of space-time. It can never leave that region. For all practical purposes the matter has disappeared from the universe. Once inside the black hole's event horizon, matter will be torn apart into its smallest subatomic components and eventually be squeezed into the singularity. As the singularity accumulates more and more matter, the size of the black hole's event horizon increases proportionally.

While everyone thought matter in a black hole was gone forever, Stephen Hawking in 1974 predicted that black holes could radiate energy away (Hawking radiation). Thus a black hole may give up some of what it had absorbed, but it does so very, very slowly. Theoretically then we say a black hole may evaporate over time by the emission of energy, but the time it would take for even a small black hole to evaporate is beyond our comprehension, on the order of a one with 67 zeros of years. Considerable work is needed to understand these strange phenomena, but for now that is where our understanding of physics has taken us.

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Where does the matter go when it is pulled into a black hole? | Science Guys | Union University, a Christian College in Tennessee

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Where does the matter go when it is pulled into a black hole? Science Guys article by The Department of Physics at Union University

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How black holes collide

Usually do not collide if they did not begin as binary stars (stars that are born together) before becoming black holes

This would result in 2 black holes really close together that would orbit around each other, similar to how they would when they were stars

They get closer and orbit faster until they collide and create a slightly larger black hole

As a result…

Gravitational waves are produced

Because the two black holes originally were orbiting around each other, they begin to move and create ripples in the fabric of space

From Einstein's general theory of relativity, he states that gravity is a phenomenon as a result of the curving of spacetime

Following his theory, the curves and bends are due to mass present in the universe. Originally, they were supposed to be one divot in space but when two masses begin to orbit each other, spacetime also bends to reflect the change in location of those objects

The fabric (spacetime) of space gets shaken and creates strong waves

360 x 10^45 W of energy is released when two black holes collide. This much energy as a result of the collision is strong enough to bend the fabric of space which allows us to detect that bend from Earth using the LIGO

We first detected a black hole collision back in 2015 using the LIGO. Ever since then, we have been discovering a handful of black hole collisions and will continue to do so as technology continues to advance

Fun fact: 2 black holes colliding together produces a lot more energy than the energy of every star in the universe added together. This is why we are able to detect if black holes collide even if they are really far away; the results are evident from very far away

https://www.youtube.com/watch?v=kEfwa7Rt3oI

Next questions: What is the significance of gravitational waves? When the fabric of space bends, matter is “attracted” to it, so when black holes create strong gravitational waves and ripples, how are the surrounding matter being affected? Are they pulled towards the black hole or pushed away (because waves usually push away)?

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How does the amount of matter the black hole consumes affect its lifespan.

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How does the amount of matter the black hole consumes affect its lifespan.

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Black holes are normally objects that are incredibly difficult to view, as they even absorb light. However one method of detecting a black hole can be found due to an area of a black hole called the accretion disk, which is a ring of material surrounding the black hole. All the material in this disk is remnants of objects that the black hole has already absorbed.

These accretion disks make black holes visible due to the fact that as the material making up the accretion disk moves closer and closer to the black hole, its speed continuously increases, creating friction and thereby heat, causing the disk to glow, and a shadow of the black hole is created and made visible.

As for the material that is fully absorbed into the black hole our current understanding of the interior of black holes dictates that once any form of material crosses the event horizon of a black hole, it is almost certainly lost forever. The only exception to this statement is a theory proposed by Steven Hawking that proposed escape from a black hole may be possible, but it would be a prolonged process

This leads to the survival of black holes, their survival is completely dependent on the amount of energy they contain, as black holes will perpetually shed their energy. The lifespan of a black hole can be compared to a timer, or better yet an hourglass. The sand plays the part of the energy the black hole possesses, and as the sand whittles down, so too does the life force of the black hole.

Black holes absorb energy by consuming the gasses and stars and any material they can pull into their event horizon. This consumption allows them to restore their stores of energy, and thereby extend their timer before they begin to die. As long as a black hole can continue to consume material, therefore gaining energy, it will continue to live on and even expand. Both the accretion disks and the black holes themselves expand as they absorb more mass. Therefore when absorbing material, a black hole will not only extend its lifespan but also expand its size as well.

The exact reasoning behind this is the process by which black holes do begin to die. Since black holes constantly shed their energy, they are thereby shedding their mass away, which means they begin to shrink bit by bit, meaning that their lifespan is solely dependent on how long they can hold out before shedding all their mass away. This means that as long as a black hole can retain its mass, and thereby size, it will be able to counteract the constant shrinking and stay alive.

Although even if black holes are constantly shedding energy and shrinking, it does not at all mean that any black holes will die any time soon. It is estimated that for a supermassive black hole, the one found at the center of many galaxies, it would take around 10¹⁰⁰ years to fully disappear. Black holes can continue resetting their timers for unfathomably long periods of time, their hourglass will not easily empty.

In conclusion, the amount of matter consumed by a black hole is directly proportional to its lifespan. The more mass consumed by a black hole, the more mass that black hole will possess, therefore taking that much longer to lose said mass, continuously cheating its death until there is no more surrounding mass to consume.

Further Question:

Why is it that black holes perpetually shed their mass away?

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Long after the last stars fade, black holes will herald the end of the universe with a spectacular show of fireworks.

Black holes are regions of space-time where gravity rules: The gravitational pull of a black hole is so strong that nothing, not even light, can escape. They range in size from stellar-mass black holes, whose masses can run from five to 100 times that of the Sun, all the way to supermassive black holes, which can reach well over a billion solar masses. Astronomers now believe supermassive black holes hide within the heart of most galaxies. (A notable exception to this rule is M33, which, despite being the third largest member of our Local Group, appears to lack a central supermassive black hole.)

Right now, the universe is in its Stelliferous Era, when stars and galaxies are continuously being born. Eventually, the ingredients to make these objects will be used up, and the stars in the night sky slowly will wink out, leaving black holes as the universe's only occupants.

But even the black holes will one day die. And when they do, these monsters won't go gently into the night. A burst of fireworks will light up the universe in the final moments of each black hole, heralding the end of the era.

Cheating death

Black holes survive by gobbling down the gas and stars around them, and it's their gluttony that gives them away. They are often surrounded by accretion disks of material they've torn apart and sucked close, like water swirling down a drain. As material draws closer, it begins to travel faster and faster, piling up around the black hole. Friction among the dust generates heat, causing the accretion disk to glow, which outlines the shadow of the black hole - or its event horizon. "It wants to hide but it does a pretty bad job of it sometimes," says Sheperd Doeleman, a black hole researcher at Harvard University and director of the Event Horizon Telescope, which snapped the first photo of a black hole in 2019.

Besides giving a black hole away, the event horizon is also the key to a black hole's death.

The material that crosses a black hole's horizon is lost forever, as nothing can escape the grip of these gluttonous monsters. At least, that's what our current understanding of gravity dictates. But this so-called point of no return fails to take quantum mechanics into account. (Physicists are still working to develop a unified theory of quantum gravity.) In 1974, Stephen Hawking proved that, from a quantum perspective, escape from a black hole is possible, though it is very slow.

While empty space may seem devoid of energy, it isn't - according to quantum mechanics, the energy of a vacuum fluctuates slightly over time. Those fluctuations manifest as pairs of particles - a particle and an antiparticle - that pop into and out of existence throughout the universe. Because energy cannot be created from nothing, one of the particles will have positive energy and the other negative. These particle pairs usually immediately annihilate one another. But if the particles appear at the boundary of a black hole's event horizon, it's possible for the particle with negative energy to fall into the black hole, while the particle with positive energy escapes. It then appears that the black hole has radiated a particle away. Einstein showed that energy and mass are proportional with his equation E = mc ². Therefore, the negative energy from the forsaken particle actually removes mass from the black hole, causing it to shrink.

But don't expect a black hole to disappear any time soon. It takes a shockingly long time for a black hole to shed all of its mass as energy via Hawking radiation. It would take 10 ¹⁰⁰ years, or a googol, for a supermassive black hole to fully disappear. "The entire age of the universe [is] a fraction of [the time] it would take," says Priyamvada Natarajan, a researcher at Yale University who probes the nature of black holes. "As far as we're concerned, it is eternity."

Death throes

Exactly how long an individual black hole lives depends strongly on its mass. The larger a black hole gets, the longer it takes to evaporate. "In that sense, [a black hole] can cheat death by growing," Doeleman says.

He compares the process to an hourglass, where the sand at the top is the amount of time a black hole has left. By gobbling down more stars and gas, a black hole continues to add sand to the hourglass of its life, even as individual particles trickle out. "As long as there is material around [to eat], the black hole can keep resetting its clock," Doeleman says. Eventually, as the universe ages, the material around a black hole will run out and its doomsday clock will start ticking.

As a black hole evaporates, it slowly shrinks and, as it loses mass, the rate of particles escaping also increases until all the remaining energy escapes at once. In the final tenth of a second of a black hole's life, "you will have a huge flash of light and energy," Natarajan says. "It's almost like a million nuclear fusion bombs going off in a very tiny region of space."

By Earth's standards, that's a lot, significantly more than the total nuclear arsenal of all nations. In astronomical terms, not so much. The most powerful supernova yet recorded (ASSASN-15lh) was 22 trillion times more explosive than a black hole will be in its final moments.
This story comes from our special January 2021 issue, "The Beginning and the End of the Universe." Click here to purchase the full issue.
It doesn't matter how small or how massive a black hole is, their closing fireworks are exactly the same. The only difference is how long it will take a black hole to explode. But once a black hole gobbles down its last meal, all that's left is for the sand grains to relentlessly tumble down until there's nothing left.

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The Beginning to the End of the Universe: How black holes die

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Back to Article List Long after the last stars fade, black holes will herald the end of the universe with a spectacular show of fireworks. Black holes are regions of space-time where gravity rules: The gravitational pull of a black hole is so strong that nothing, not even light, can escape.

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What would gravitational waves provide in terms of exploring the universe?

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What would gravitational waves provide in terms of exploring the universe?

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Allow us to explore fundamental physics

Potentially see back to the big bang

LIGO

gets signals when high levels of gravitational waves are present

Went off when two black holes collided after circling each other

In next two years should be sensitive enough to detect gravitational waves from any colliding neutron stars within the nearest 300,000 galaxies

Gravitational waves from death spiral of two neutron stars

Colliding neutron stars let out hot bright matter

Studying these explosions and the gravitational waves could help us further understand short gamma ray bursts and where earths heavy metals such as  gold and uranium are forged

Dark Energy

Causing the universe expansion to accelerate

Looking at the shape of gravitational waves can tell us figure out the size of black holes and how loud the event was in that area

This could provide us with information to how space expanded while the waves were reaching us giving us a measurement of dark energy’s effect on space

In the future

Gravitational wave detectors that can work at smaller wavelengths then LIGO(allows us to find primordial gravitational waves from very small universes

With the help of gravitational waves we can currently see as far back as 380,000 years after the big bang, we can detect weather. The gravitational waves are currently helping scientists understand why merging black holes are producing gamma rays. The more we study the gravitational waves the more we are learning and exploring in our universe.

Next questions:

What is a neutron star? why are they significant?

What happens when space-time ripples?

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Two black holes became one

Julian Stratenschulte/DPA/Corbis

"THERE'S going to be a revolution." So says Erik Katsavounidis of MIT, one of the team behind the long-awaited discovery of gravitational waves.

On 11 February, the Laser Interferometer Gravitational-Wave observatory, or LIGO, announced it had spotted gravitational waves, the stretching and squeezing of space-time caused by the movement of massive objects.

Watch the exclusive world premiere on 7 February 2017

The announcement caused a sensation among physicists and astronomers across the world, and they are now gearing up to exploit this new window on the universe. Gravitational waves will allow us to explore fundamental physics, examine the weirdest objects in the universe and possibly even peer back to the universe's earliest moments. "We can potentially see almost all the way to the big bang," says Dejan Stojkovic of the State University of New York in Buffalo.

The signal was picked up by LIGO's two observatories in Hanford, Washington, and Livingston, Louisiana, on 14 September 2015. It was created by two black holes colliding, each about 30 times the mass of the sun. The details of the signal suggest they circled each other closer and closer until they finally merged into one.

This immediately resolved one open question for astronomers. Before the signal came in, the very existence of such black hole binaries was contested. Because they are dark, black holes of these masses are almost impossible to spot unless something bright - like a star - orbits them.

"Signals from black hole mergers could help us understand the nature of dark energy"

The next target is to observe gravitational waves from the death spiral of two neutron stars. Unlike black holes, which hide their mass behind an event horizon even as they crash, colliding neutron stars spew hot, bright matter across space, which could help us explore other mysteries. For example, studying these explosions may explain short gamma-ray bursts - mysterious and incredibly bright electromagnetic phenomena. They might also help explain where much of the universe's heavy elements, like uranium, thorium and gold, are forged.

Within the next two years, LIGO should be sensitive enough to detect gravitational waves from any neutron star mergers that happen within the nearest 300,000 galaxies. That means we should see about one signal per month.

These single event detections are just the start, however. Put several together and we should be able to get new insights into the history and composition of the universe as a whole, says Avi Loeb of Harvard University. The signals from a number of black hole mergers, for example, can be combined to help understand the nature of dark energy, which is causing the universe's expansion to accelerate.

LIGO has a big reach

Caltech/LIGO

From the "shape" of the signal - how the waves' frequency and volume rise and fall - we can discern the sizes of the black holes involved, and determine how loud the event was at its source. Comparing how powerful it really was to the faint vibrations LIGO detected tells us how far away it occurred. Combined with observations from standard telescopes, this can tell us how space has expanded during the time the waves took to reach us, providing a measure of dark energy's effect on space.

This measure should be stronger and more reliable than anything we have used so far. Spotting just a few black hole mergers would change everything, Loeb says. "If you have tens of them, it will be a new branch in cosmology."

Other researchers are hoping to use gravitational wave signals to put Einstein's general theory of relativity to even more stringent tests. One way is through the equivalence principle, an assumption that gravity affects all masses in the same way. "In the age of GPS and space travel, where even minute deviations from the assumed theory of gravity would have major consequences, it is of enormous importance," says Xue-Feng Wu of Purple Mountain Observatory in Nanjing, China.

Erminia Calabrese, an astronomer at the University of Oxford, sees gravitational waves as a way to check whether gravity behaves as relativity predicts it should over large distances. "If their strength fell off with distance in a surprising way we could detect this with the upcoming LIGO data," she says.

More detectors

LIGO's success could see an explosion in gravitational wave detection. India, for example, has long been slated to host a third LIGO detector. Funding has yet to materialise, but after last Thursday's announcement, Indian prime minister Narendra Modi tweeted that he hopes "to move forward to make even bigger contribution with an advanced gravitational wave detector in the country".

Other types of detectors could come on the scene, too. "Now that we know gravitational waves exist, it will be much easier to convince people to invest money and make all kinds of gravitational wave detectors," Stojkovic says.

New designs are already in the pipeline. The European Space Agency is about to start tests of equipment for the Evolved Laser Interferometer Antenna (eLISA), a huge, space-based detector. A preparatory experiment, LISA Pathfinder, is in orbit and will begin tests next month. NASA pulled out of the project in 2011, but has now formed a committee to look into how it might rejoin.

Further ahead, we might see more sensitive gravitational wave detectors, working at shorter wavelengths than LIGO. These may allow us to sense primordial gravitational waves from the very young universe. These waves should have been produced in the period of inflation - the tremendous growth spurt in the first instants after the big bang. Unlike photons and other electromagnetic radiation, they would have travelled freely through the newborn universe. At the moment we can only see as far back as 380,000 years after the big bang, when the universe became transparent to light.

Gravitational waves may even point the way toward a grand unified theory of the universe. Theory suggests that at some point in the universe's history, all four fundamental forces were united into a single force. As the universe expanded and cooled, the forces split off from one another in a series of as-yet poorly understood events. "Gravitational wave observatories that can detect much shorter wavelengths could probe those," Stojkovic says.

For now, physicists already have a mystery to solve: a faint gamma-ray burst that seems to be related to LIGO's signal. No one expected merging black holes to give off gamma rays. "Everything lines up except the physics," says Valerie Connaughton of NASA's Marshall Spaceflight Center.

LIGO team member Daniel Holz at the University of Chicago reckons this surprise is just the beginning. "Every time we've opened a window to the universe, we've found all sorts of unexpected things," Holz says. "I'd be surprised if I wasn't surprised."
This article appeared in print under the headline "Surfing gravity's waves"

Topics:

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What will gravitational waves tell us about the universe?

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The discovery of gravitational waves might give us a view of the cosmos that stretches all the way back to the big bang and tell us if there's a theory of everything

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15 years of radio data reveals evidence of space-time murmur

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15 years of radio data reveals evidence of space-time murmur

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Scientists have found evidence of gravitational or ripples in the fabric of space-time

Movement of black holes and other objects in space can create ripples in the universe called gravitational waves.

On June 28, 2023 scientists announced the first evidence of a background of long-wavelength gravitational waves fills the cosmos

These waves are created over long periods of time by supermassive black holes (up to 3 billions of times the mass of our sun)

The sound of a gravitational wave is the same as hearing the hum of a large group of people talking at a party.

The detection of these waves will help scientists better understand how gravitational waves are created and what happens to them as they spread the universe

Could also be used to study supermassive black hole mergers

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) was the organization that presented this recently discovered evidence in a series of papers published in the Astrophysical Journal Letters.

This Organization has spent more than 15 years trying to collect high-quality data from ground-based radio telescopes

This discovery made from the NANOGrav complements the first-ever detection of gravitational waves in 2015 by LIGO

The waves detected by LIGO were much shorter compared to the newer discovery and were from black holes only about 30 times the mass of our Sun.

Now NASA is focusing on the ESA (European Space Agency)-led Laser Interferometer Space Antenna mission, a space based observatory that will detect gravitational waves that are in a wavelength range between the NANOGrav and LIGO ones.

Next Question:

How are gravitational waves detected with use of ground-based radio telescopes?

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15 Years of Radio Data Reveals Evidence of Space-Time Murmur

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Scientists have found evidence of a universal background of gravitational waves, or ripples in the fabric of space-time.

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How do quasars affect the evolution of galaxies?

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How do quasars affect the evolution of galaxies?

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Quasars and galaxies directly affect each other, Galiaxies supply fuel to the black holes

the quasar heat and disrupts the gas clouds in the galaxy

Athe blacnace between these two processes helps explain as to the holes seemas to always be about 1/200 the mass of the starts that surround the black hole

Quaser have several reduced in numbers, billions of years agi they were far more common

Some believe that they mark an early state in the formation of galaxies

Quasars were more likely to be active when the universe was young and fuel for their accretion disk was more available

The activity of quasar can be re triggered by a collision between two galaxies

This collision provides more fuel to feed that black holes

Next Questions

What happens when a black hole reaches capacity?

How much fuel can a single galaxy provide?

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Learning Objectives

By the end of this section, you will be able to:

Trace the rise and fall of quasars over cosmic time

Describe some of the ways in which galaxies and black holes influence each other's growth

Describe some ways the first black holes may have formed

Explain why some black holes are not producing quasar emission but rather are quiescent

The quasars' brilliance and large distance make them ideal probes of the far reaches of the universe and its remote past. Recall that when first introducing quasars, we mentioned that they generally tend to be far away. When we see extremely distant objects, we are seeing them as they were long ago. Radiation from a quasar 8 billion light-years away is telling us what that quasar and its environment were like 8 billion years ago, much closer to the time that the galaxy that surrounds it first formed. Astronomers have now detected light emitted from quasars that were already formed only a few hundred million years after the universe began its expansion 13.8 billion years ago. Thus, they give us a remarkable opportunity to learn about the time when large structures were first assembling in the cosmos.

Quasars provide compelling evidence that we live in an evolving universe-one that changes with time. They tell us that astronomers living billions of years ago would have seen a universe that is very different from the universe of today. Counts of the number of quasars at different redshifts (and thus at different times in the evolution of the universe) show us how dramatic these changes are ( Figure 27.14). We now know that the number of quasars was greatest at the time when the universe was only 20% of its present age.

As you can see, the drop-off in the numbers of quasars as time gets nearer to the present day is quite abrupt. Observations also show that the emission from the accretion disks around the most massive black holes peaks early and then fades. The most powerful quasars are seen only at early times. In order to explain this result, we make use of our model of the energy source of the quasars-namely that quasars are black holes with enough fuel to make a brilliant accretion disk right around them.

The fact that there were more quasars long ago (far away) than there are today (nearby) could be explained if there was more material available to be accreted by black holes early in the history of the universe. You might say that the quasars were more active when their black holes had fuel for their "energy-producing engines." If that fuel was mostly consumed in the first few billion years after the universe began its expansion, then later in its life, a "hungry" black hole would have very little left with which to light up the galaxy's central regions.

In other words, if matter in the accretion disk is continually being depleted by falling into the black hole or being blown out from the galaxy in the form of jets, then a quasar can continue to radiate only as long as new gas is available to replenish the accretion disk.

In fact, there was more gas around to be accreted early in the history of the universe. Back then, most gas had not yet collapsed to form stars, so there was more fuel available for both the feeding of black holes and the forming of new stars. Much of that fuel was subsequently consumed in the formation of stars during the first few billion years after the universe began its expansion. Later in its life, a galaxy would have little left to feed a hungry black hole or to form more new stars. As we see from Figure 27.14, both star formation and black hole growth peaked together when the universe was about 2 billion years old. Ever since, both have been in sharp decline. We are late to the party of the galaxies and have missed some of the early excitement.

Observations of nearer galaxies (seen later in time) indicate that there is another source of fuel for the central black holes-the collision of galaxies. If two galaxies of similar mass collide and merge, or if a smaller galaxy is pulled into a larger one, then gas and dust from one may come close enough to the black hole in the other to be devoured by it and so provide the necessary fuel. Astronomers have found that collisions were also much more common early in the history of the universe than they are today. There were more small galaxies in those early times because over time, as we shall see (in The Evolution and Distribution of Galaxies), small galaxies tend to combine into larger ones. Again, this means that we would expect to see more quasars long ago (far away) than we do today (nearby)-as we in fact do.

Once black hole masses began to be measured reliably in the late 1990s, they posed an enigma. It looked as though the mass of the central black hole depended on the mass of the galaxy. The black holes in galaxies always seem to be just 1/200 the mass of the galaxy they live in. This result is shown schematically in Figure 27.15, and some of the observations are plotted in Figure 27.16.

Correlation between the Mass of the Central Black Hole and the Mass Contained within the Bulge of Stars Surrounding the Black Hole, Using Data from Real Galaxies.

Somehow black hole mass and the mass of the surrounding bulge of stars are connected. But why does this correlation exist? Unfortunately, astronomers do not yet know the answer to this question. We do know, however, that the black hole can influence the rate of star formation in the galaxy, and that the properties of the surrounding galaxy can influence how fast the black hole grows. Let's see how these processes work.

Let's look first at how the surrounding galaxy might influence the growth and size of the black hole. Without large quantities of fresh "food," the surroundings of black holes glow only weakly as bits of local material spiral inward toward the black hole. So somehow large amounts of gas have to find their way to the black hole from the galaxy in order to feed the quasar and make it grow and give off the energy to be noticed. Where does this "food" for the black hole come from originally and how might it be replenished? The jury is still out, but the options are pretty clear.

One obvious source of fuel for the black hole is matter from the host galaxy itself. Galaxies start out with large amounts of interstellar gas and dust, and at least some of this interstellar matter is gradually converted into stars as the galaxy evolves. On the other hand, as stars go through their lives and die, they lose mass all the time into the space between them, thereby returning some of the gas and dust to the interstellar medium. We expect to find more gas and dust in the central regions early in a galaxy's life than later on, when much of it has been converted into stars. Any of the interstellar matter that ventures too close to the black hole may be accreted by it. This means that we would expect that the number and luminosity of quasars powered in this way would decline with time. And as we have seen, that is just what we find.

Today both elliptical galaxies and the nuclear bulges of spiral galaxies have very little raw material left to serve as a source of fuel for the black hole. And most of the giant black holes in nearby galaxies, including the one in our own Milky Way, are now dark and relatively quiet-mere shadows of their former selves. So that fits with our observations.

We should note that even if you have a quiescent supermassive black hole, a star in the area could occasionally get close to it. Then the powerful tidal forces of the black hole can pull the whole star apart into a stream of gas. This stream quickly forms an accretion disk that gives off energy in the normal way and makes the black hole region into a temporary quasar. However, the material will fall into the black hole after only a few weeks or months. The black hole then goes back into its lurking, quiescent state, until another victim wanders by.

This sort of "cannibal" event happens only once every 100,000 years or so in a typical galaxy. But we can monitor millions of galaxies in the sky, so a few of these "tidal disruption events" are found each year ( Figure 27.17). However, these individual events, dramatic as they are, are too rare to account for the huge masses of the central black holes.

Another source of fuel for the black hole is the collision of its host galaxy with another galaxy. Some of the brightest galaxies turn out, when a detailed picture is taken, to be pairs of colliding galaxies. And most of them have quasars inside them, not easily visible to us because they are buried by enormous amounts of dust and gas.

A collision between two cars creates quite a mess, pushing parts out of their regular place. In the same way, if two galaxies collide and merge, then gas and dust (though not so much the stars) can get pushed out of their regular orbits. Some may veer close enough to the black hole in one galaxy or the other to be devoured by it and so provide the necessary fuel to power a quasar. As we saw, galaxy collisions and mergers happened most frequently when the universe was young and probably help account for the fact that quasars were most common when the universe was only about 20% of its current age.

Collisions in today's universe are less frequent, but they do happen. Once a galaxy reaches the size of the Milky Way, most of the galaxies it merges with will be much smaller galaxies- dwarf galaxies (see the chapter on Galaxies). These don't disrupt the big galaxy much, but they can supply some additional gas to its black hole.

By the way, if two galaxies, each of which contains a black hole, collide, then the two black holes may merge and form an even larger black hole ( Figure 27.18). In this process they will emit a burst of gravitational waves. One of the main goals of the European Space Agency's planned LISA (Laser Interferometer Space Antenna) mission is to detect the gravitational wave signals from the merging of supermassive black holes.

We have seen that the material in galaxies can influence the growth of the black hole. The black hole in turn can also influence the galaxy in which it resides. It can do so in three ways: through its jets, through winds of particles that manage to stream away from the accretion disk, and through radiation from the accretion disk. As they stream away from the black hole, all three can either promote star formation by compressing the surrounding gas and dust-or instead suppress star formation by heating the surrounding gas and shredding molecular clouds, thereby inhibiting or preventing star formation. The outflowing energy can even be enough to halt the accretion of new material and starve the black hole of fuel. Astronomers are still trying to evaluate the relative importance of these effects in determining the overall evolution of galactic bulges and the rates of star formation.

In summary, we have seen how galaxies and supermassive black holes can each influence the evolution of the other: the galaxy supplies fuel to the black hole, and the quasar can either support or suppress star formation. The balance of these processes probably helps account for the correlation between black hole and bulge masses, but there are as yet no theories that explain quantitatively and in detail why the correlation between black hole and bulge masses is as tight as it is or why the black hole mass is always about 1/200 times the mass of the bulge.

While the connection between quasars and galaxies is increasingly clear, the biggest puzzle of all-namely, how the supermassive black holes in galaxies got started-remains unsolved. Observations show that they existed when the universe was very young. One dramatic example is the discovery of a quasar that was already shining when the universe was only 700 million years old. What does it take to create a large black hole so quickly? A related problem is that in order to eventually build black holes containing more than 2 billion solar masses, it is necessary to have giant "seed" black holes with masses at least 2000 times the mass of the Sun-and they must somehow have been created shortly after the expansion of the universe began.

Astronomers are now working actively to develop models for how these seed black holes might have formed. Theories suggest that galaxies formed from collapsing clouds of dark matter and gas. Some of the gas formed stars, but perhaps some of the gas settled to the center where it became so concentrated that it formed a black hole. If this happened, the black hole could form right away-although this requires that the gas should not be rotating very much initially.

A more likely scenario is that the gas will have some angular momentum (rotation) that will prevent direct collapse to a black hole. In that case, the very first generation of stars will form, and some of them, according to calculations, will have masses hundreds of times that of the Sun. When these stars finish burning hydrogen, just a few million years later, the supernovae they end with will create black holes a hundred or so times the mass of the Sun. These can then merge with others or accrete the rich gas supply available at these early times.

The challenge is growing these smaller black holes quickly enough to make the much larger black holes we see a few hundred million years later. It turns out to be difficult because there are limits on how fast they can accrete matter. These should make sense to you from what we discussed earlier in the chapter. If the rate of accretion becomes too high, then the energy streaming outward from the black hole's accretion disk will become so strong as to blow away the infalling matter.

What if, instead, a collapsing gas cloud doesn't form a black hole directly or break up and form a group of regular stars, but stays together and makes one fairly massive star embedded within a dense cluster of thousands of lower mass stars and large quantities of dense gas? The massive star will have a short lifetime and will soon collapse to become a black hole. It can then begin to attract the dense gas surrounding it. But calculations show that the gravitational attraction of the many nearby stars will cause the black hole to zigzag randomly within the cluster and will prevent the formation of an accretion disk. If there is no accretion disk, then matter can fall freely into the black hole from all directions. Calculations suggest that under these conditions, a black hole even as small as 10 times the mass of the Sun could grow to more than 10 billion times the mass of the Sun by the time the universe is a billion years old.

Scientists are exploring other ideas for how to form the seeds of supermassive black holes, and this remains a very active field of research. Whatever mechanism caused the rapid formation of these supermassive black holes, they do give us a way to observe the youthful universe when it was only about five percent as old as it is now.

Quasars and galaxies affect each other: the galaxy supplies fuel to the black hole, and the quasar heats and disrupts the gas clouds in the galaxy. The balance between these two processes probably helps explain why the black hole seems always to be about 1/200 the mass of the spherical bulge of stars that surrounds the black hole.

Quasars were much more common billions of years ago than they are now, and astronomers speculate that they mark an early stage in the formation of galaxies. Quasars were more likely to be active when the universe was young and fuel for their accretion disk was more available.

Quasar activity can be re-triggered by a collision between two galaxies, which provides a new source of fuel to feed the black hole.

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27.3 Quasars as Probes of Evolution in the Universe

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By the end of this section, you will be able to: Trace the rise and fall of quasars over cosmic time Describe some of the ways in which galaxies and black holes influence each other's growth Describe some ways the first black holes may have formed Explain why some black holes are not producing quasar emission but rather are quiescent The quasars' brilliance and large distance make them ideal probes of the far reaches of the universe and its remote past.

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This is due Hawking radiation which was a concept developed by Stephen Hawking to explain the fact that black holes will eventually evaporate along with everything it swallowed in its lifetime

Black holes were thought to be completely black and could not be in equilibrium with thermal energy until Hawking found there to be radiation coming from a black hole during his research. The radiation will release energy and therefore shrink the black hole until nothing is left. Scientists originally thought that energy would be lost but Hawking concluded that the energy released cannot be used. He says it is similar to “burning an encyclopedia” where it originally had information but is now in a different state which cannot be converted back to its original form.

Stephen Hawking combined quantum theory and general relativity to consider particles escaping the black hole. Using quantum theory that suggests that there are particle-antiparticle pairs, Hawking concluded that if these pairs were at the edge of the event horizon, there is a chance that the negative antiparticle will fall into the black hole while the other positive particle escapes into space. The loss of particles and energy will result in the slow but eventual evaporation of a black hole.

The escaped particle is what scientists call Hawking radiation

Black holes have a temperature, although only slightly higher than absolute 0. Hawking was able to show that the amount of energy/radiation a black hole is able to release is inversely proportional to the mass of the black hole. This means that the smaller the black hole, the more energy it is able to release and the quicker it will evaporate and also that the temperature emitted from the black hole is due to Hawking radiation.

Researchers were able to create a similar phenomena of smaller black holes in a lab which proved that radiation is constant and does not grow over time. Proving Hawking radiation to be true.

Next questions: How were researchers able to create a similar lab-made black hole to prove Hawking’s theory of Hawking radiation? What else has this makeshift black hole helped with in the discovery of the nature of other black holes?

https://www.sciencefocus.com/space/what-is-hawking-radiation

https://www.bbvaopenmind.com/en/science/physics/stephen-hawking-and-the-history-of-black-holes/

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Stephen Hawking on black holes - Professor Stephen Hawking

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Neutron stars

Ancient remnants of stars that have reached their full evolutionary possibilities (ran out of fuel)

Very dense

About 12.5 miles in diameter

1.5 times the mass of our sun

Produce massive gravitational pull for their size(more than earth)

Many are undetectable because do not produce much light

They sit around supernovas emitting x rays

More often found spinning in extreme magnetic fields

In binary systems they often accumulate materials from nearby companions then emit electromagnetic radiation powered by the gravitational energy that was consumed from the accumulated materials

Pulsars

Neutron stars that are rotating producing light

Strong gravitational forces

Rotate on an axis and light only visible when pointed towards you (similar to lighthouses)

Magnetars

Magnetic field 100 times stronger than a normal neutron star

Crust of star goes under a lot of strain and small movements can cause huge amounts of released energy in forms of electromagnetic radiation

SGR 1806-20 a magnetar had an explosion that released more energy than the sun in past 100,000 years

next question: How do neutron stars turn into pulsars and magnetars?

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A neutron star is the densest object astronomers can observe directly, crushing half a million times Earth's mass into a sphere about 12 miles across, or similar in size to Manhattan Island, as shown in this illustration. (Credit: NASA's Goddard Space Flight Center)

Neutron stars are formed when a massive star runs out of fuel and collapses. The very central region of the star – the core – collapses, crushing together every proton and electron into a neutron. If the core of the collapsing star is between about 1 and 3 solar masses, these newly-created neutrons can stop the collapse, leaving behind a neutron star. (Stars with higher masses will continue to collapse into stellar-mass black holes.)

This collapse leaves behind the most dense object known – an object with the mass of a sun squished down to the size of a city. These stellar remnants measure about 20 kilometers (12.5 miles) across. One sugar cube of neutron star material would weigh about 1 trillion kilograms (or 1 billion tons) on Earth – about as much as a mountain.

This diagram of a pulsar shows the neutron star with a strong magnetic field (field lines shown in blue) and a beam of light along the magnetic axis. As the neutron star spins, the magnetic field spins with it, sweeping that beam through space. If that beam sweeps over Earth, we see it as a regular pulse of light. (Credit: NASA/Goddard Space Flight Center Conceptual Image Lab)

Since neutron stars began their existence as stars, they are found scattered throughout the galaxy in the same places where we find stars. And like stars, they can be found by themselves or in binary systems with a companion.

Many neutron stars are likely undetectable because they simply do not emit enough radiation. However, under certain conditions, they can be easily observed. A handful of neutron stars have been found sitting at the centers of supernova remnants quietly emitting X-rays. More often, though, neutron stars are found spinning wildly with extreme magnetic fields as pulsars or magnetars. In binary systems, some neutron stars can be found accreting materials from their companions, emitting electromagnetic radiation powered by the gravitational energy of the accreting material. Below we introduce two general classes of non-quiet neutron star â€" pulsars and magnetars.

Pulsars

Most neutron stars are observed as pulsars. Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds. Pulsars have very strong magnetic fields which funnel jets of particles out along the two magnetic poles. These accelerated particles produce very powerful beams of light. Often, the magnetic field is not aligned with the spin axis, so those beams of particles and light are swept around as the star rotates. When the beam crosses our line-of-sight, we see a pulse â€" in other words, we see pulsars turn on and off as the beam sweeps over Earth.

One way to think of a pulsar is like a lighthouse. At night, a lighthouse emits a beam of light that sweeps across the sky. Even though the light is constantly shining, you only see the beam when it is pointing directly in your direction. The video below is an animation of a neutron star showing the magnetic field rotating with the star. Partway through, the point-of-view changes so that we can see the beams of light sweeping across our line of sight – this is how a pulsar pulses.

Magnetars

Another type of neutron star is called a magnetar. In a typical neutron star, the magnetic field is trillions of times that of the Earth's magnetic field; however, in a magnetar, the magnetic field is another 1000 times stronger.

In all neutron stars, the crust of the star is locked together with the magnetic field so that any change in one affects the other. The crust is under an immense amount of strain, and a small movement of the crust can be explosive. But since the crust and magnetic field are tied, that explosion ripples through the magnetic field. In a magnetar, with its huge magnetic field, movements in the crust cause the neutron star to release a vast amount of energy in the form of electromagnetic radiation. A magnetar called SGR 1806-20 had a burst where in one-tenth of a second it released more energy than the sun has emitted in the last 100,000 years!

A rupture in the crust of a highly magnetized neutron star, shown here in an artist's rendering, can trigger high-energy eruptions. (Credit: NASA's Goddard Space Flight Center/S. Wiessinger)

Text updated: March 2017
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This site is intended for students age 14 and up, and for anyone interested in learning about our universe.

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Lab-grown black hole may prove Stephen Hawking’s most challenging theory right

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Lab-grown black hole may prove Stephen Hawking’s most challenging theory right

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Scientists have created a lab-grown black hole experiment to test on of Hawking’s most famous theories and it turns out it behaves just like his predictions

The experiment was created by using a single-file chain of atoms to stimulate the event horizon of a black hole has added further evidence to the theory; stating that black holes give off a faint glow of radiation from virtual particles randomly forming into existence new their boundaries.

Researchers also found that most of the photons (light particles) should be produced around the cosmic monsters’ edges.

In 1974, Stephen Hawking's predicted that the extreme gravitational forces felt in the middle of black holes would create photons (light particles) into existence.

Physicists are interested in Hawking’s prediction because it is made at the extreme boundary of physics’ two big theories; Einstein’s theory of general relativity (that describes the world of large objects) and quantum mechanics (which discusses the behaviors of the smallest particles)

Detecting these hypothesized light directly is something astrophysicists are unlikely ever to achieve. Many posed challenges come in the way, for instance traveling to a black hole (the closest one being 1,566 light-years away from the Earth) and once individuals end up making it to a black hole then they will most probably end up getting immensely pulled by the gravitational pull. Additionally, these Hawking’s photons around black holes are thought to be really small

In the absence of a real black hole, physicists have begun looking for Hawking radiation in experiments.

In 2021, researchers used a one-dimensional row of 8,000 super-cooled, laser-confined atoms of the element rubidium, to create virtual particles in the form of wave-like excitation's along the chain.

Another experiment achieved a similar outcome by adjusting the electron movement between atoms, creating an artificial version of a black hole’s space-time warping event horizon

When part of the chain crossed this stimulated horizon, researchers observed a temperature spike, mimicking the infrared radiation emitted around black holes

The findings of these experiments indicate a potential relation between Hawking radiation and quantum entanglement (occurs between particles on either side of an event horizon)

For the production of Hawking radiation, there needs to be a change in specific energy configurations of space-time

Notably, the model used in the experiment critically lacked the powerful gravity distortions produced by a black hole. So the connection between the theory of quantum gravity and the potential occurrence of naturally-produced Hawking radiation are still unclear.

Next Question:

How does the absence of powerful gravity distortions on the experimental model impact the understanding of the results?

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Scientists have created a lab-grown black hole analog to test one of Stephen Hawking's most famous theories - and it behaves just how he predicted.

The experiment, created by using a single-file chain of atoms to simulate the event horizon of a black hole, has added further evidence to Hawking's theory that black holes should emit a faint glow of radiation from virtual particles randomly popping into existence near their boundaries.

What's more, the researchers found that most of the light particles, or photons, should be produced around the cosmic monsters' edges. The team published their findings Nov. 8 in the journal Physical Review Research.
Related: Black holes: Everything you need to know
According to quantum field theory, there is no such thing as an empty vacuum. Space is instead teeming with tiny vibrations that, if imbued with enough energy, randomly burst into virtual particles - particle-antiparticle pairs that almost immediately annihilate each other, producing light. In 1974, Stephen Hawking predicted that the extreme gravitational force felt at the mouths of black holes - their event horizons - would summon photons into existence in this way. Gravity, according to Einstein's theory of general relativity, distorts space-time, so that quantum fields get more warped the closer they get to the immense gravitational tug of a black hole's singularity.

Because of the uncertainty and weirdness of quantum mechanics, this warping creates uneven pockets of differently moving time and subsequent spikes of energy across the field. It is these energy mismatches that make virtual particles emerge from what appears to be nothing at the fringes of black holes, before annihilating themselves to produce a faint glow called Hawking radiation.

Physicists are interested in Hawking's prediction because it is made at the extreme boundary of physics' two grand but currently irreconcilable theories: Einstein's theory of general relativity, which describes the world of large objects, and quantum mechanics, which details the strange behavior of the smallest particles.
Read more:

(Image credit: EHT Collaboration)

Dead and alive at the same time: Black holes have quantum properties
But detecting the hypothesized light directly is something astrophysicists are unlikely to ever achieve. Firstly, there are the considerable challenges posed both by traveling to a black hole - the closest known one being 1,566 light-years from Earth - and, once there, not getting sucked in and spaghettified by its immense gravitational pull. Secondly, the number of Hawking photons springing into existence around black holes is thought to be tiny; and in most cases would be drowned out by other light-producing effects, such as the high-energy X-rays spat out from matter swirling around the black hole's precipice.

In the absence of a real black hole, physicists have begun looking for Hawking radiation in experiments that simulate their extreme conditions. In 2021, scientists used a one-dimensional row of 8,000 supercooled, laser-confined atoms of the element rubidium, a soft metal, to create virtual particles in the form of wave-like excitations along the chain.
Originally published on LiveScience. Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community@space.com.
Now, another atom-chain experiment has achieved a similar feat, this time by tuning the ease at which electrons can hop from one atom to the next in the line, creating a synthetic version of a black hole's space-time warping event horizon. After tuning this chain so that part of it fell over the simulated event horizon, the researchers recorded a spike in temperature in the chain - a result which mimicked the infrared radiation produced around black holes. The finding suggests that Hawking radiation could emerge as an effect of quantum entanglement between particles positioned on either side of an event horizon.

Interestingly, the effect only emerged when the amplitude of the hops transitioned from a few set configurations of flat space-time to a warped one - suggesting that Hawking radiation requires a change in specific energy configurations of space-time to be produced. As the powerful gravity distortions produced by the black hole are absent from the model, what this means for a theory of quantum gravity and for potential naturally-produced real Hawking radiation is unclear, but it nonetheless offers a tantalizing glimpse at previously unexplored physics.

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Lab-grown black hole may prove Stephen Hawking's most challenging theory right

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Scientists have created a lab-grown black hole analog to test one of Stephen Hawking's most famous theories - and it behaves just how he predicted. The experiment, created by using a single-file chain of atoms to simulate the event horizon of a black hole, has added further evidence to Hawking's theory that black holes should emit a faint glow of radiation from virtual particles randomly popping into existence near their boundaries.

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Is there a limit to how large a black hole can become? 

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Is there a limit to how large a black hole can become? 

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Black holes form in the final moments of a massive star’s life

They grow my consuming matter within their event horizon, where gravity is extremely strong

Medium-mass black holes, known as stellar mass, can grow larger by consuming other black holes, especially during galaxy mergers

Over time, they can evolve into supermassive black holes found at the centers of galaxies

Ultra-massive black holes, exemplified by PKS 0745 in the Puppis constellation, are even larger than supermassive black holes

NASA’s 2012 survey revealed that some of PKS 0745’s black holes are ten times more massive than previously thought

Ultra-massive black holes can have masses between ten and forty billion times that of the Sun

They contain an unusually contain large amounts of hot gas, leading to diffuse x-ray emissions when consuming material

Stellar-mass black holes range from four to ten solar masses, while supermassive ones can be hundreds of millions to a billion solar masses

Ultra-massive black holes challenge previous expectations, raising questions about growth limits

Yale University researchers found that the growth of the most massive black holes appears to stall after reaching about ten billion solar masses

The reason for this slowdown may be related to the immense energy radiated by these ultra-massive black holes.

While the research suggests a limit to black hole growth, the discovery of ultra-massive black holes larger than expected raises the possibility that there might be no upper limit

Astronomers are now reconsidering whether black holes continue growing indefinitely or if they self-destruct due to energy radiation.

Next Question:

What is the role of hot gas surrounding ultra-massive black holes, how does it influence their behavior and emissions?

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Is There a Limit to How Large Black Holes Can Become?

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A black hole, by nature, is an extreme object born within the final, volatile few moments of a massive star’s life. Skipping from the first chapter dealing with their formation, to the last: After birth, black holes bide their time by consuming all matter that comes within the range of their event horizon (the region where the gravitational […]

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Like all neutron stars pulsars go through the same process at the start of their lives

Stars to neutron stars

Made when stars 4-8 times the sun's mass lose their fuel for nuclear fission

Fusion of light to heavier elements stops, leading to a slowing in the production of energy to the supports that protects the star from its massive inward pressure

The star starts to collapse

Then outer crust will break off during a supernova explosion breaking down the star

This makes the neutron star(the collapse caused protons and newtons to bond together)

Neutron stars -> pulsars

When to core of the neutron star starts to break down and collapse it causes the star to begin to spin

Once the neutron star has begun its process it begins to start to gather materials from other companions

This then begins a transfer of angular momentum from a companion star and is what causes the star to spin faster and increases rotation speeds

A pulsar's life doesn't last forever though. A pulsar emitted radiation is powered by its magnetic field and at which it spins. They then become invisible to us even with the help of telescopes. Scientists call this stage the pulsar graveyard.

When a pulsar is young it is always seen spinning really fast and radiating a lot of energy (often after a supernova) this typical last for a few hundred thousand years

A Pulsar is the recognized as middle age when they begin to slow down and begin to only emit radio waves(these stage will last 10 of millions of years before dying being added to the pulsar graveyard)

Being brought back to life

If a pulsar in the graveyard sits near a good companion it can “recycle” the pulsar

It can help the dead pulsar spin again by sending materials and energy

Once the pulsar has been brought back to life it will start emitting X-rays again putting it back into the young age category

This recycling can happen at any time during a pulsars life and can happen repetitively

Next question:

How are magnetars made? What evolutionary pathways do they take to be considered magnetars?

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These ‘cosmic lighthouses’ can spin as fast as 700 rotations per second.

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How Ground-based Radio Telescopes Detect Gravitational Waves 

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How Ground-based Radio Telescopes Detect Gravitational Waves 

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The NANOGrav (North American Nanohertz Observatory for Gravitational Waves) is a ground-based radio telescope that specializes in low frequency gravitational waves, different from LIGO which is more of a laser-based piece of technology

How NANOGrav works:

It studies signals from pulsars as they are known to be the universe’s clock

Due to the fact that pulsars rapidly and repeatedly emit radio waves that are consistent when observed by the NANOGrav. These radio waves that are detected are precisely spaced, similar to a clock ticking at a steady pace. They track more than one pulsar to make sure their information is correct

Consistent pulsar radio waves are called “pulsar timing array”

They are currently studying 47 different pulsars to make sure their detections are accurate. Only the most stable, well studied, and consistent pulsars

The gravitational waves/ripples in spacetime cause interferences with the time the radio waves are received on Earth that were emitted from distant pulsars. When gravitational waves ripple through spacetime, it stretches or compresses time and therefore creates an inconsistency in the pulsar's predictable radio waves

This is a sign that a low frequency gravitational wave is present. This helps establish that gravitational waves do exist as a result of black holes and also proving Einstein was correct with his theory of gravitational waves and spacetime

Through deep data analysis and removing local errors produced from the solar system or errors from data collection, they are able to confirm gravitational waves

Next Questions: Are there other ground-based telescopes? Do they use the same strategies as NANOGrav to use the pulsar timing array or are there more ways to detect gravitational waves?

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NANOGrav Finds Possible ‘First Hints’ of Low-Frequency Gravitational Wave Background

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In data gathered and analyzed over 13 years, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has found an intriguing low-frequency signal that may be attributable to gravitational waves.

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What is a magnetar and how do they form? 

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What is a magnetar and how do they form? 

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Magnetars are a type of neutron star with incredibly strong magnetic fields, the strongest observed in the universe

Magnetars emit eruptive X-rays and gamma rays

These are associated with bursts of intense radiation, likely due to the ultra-strong magnetic fields

Magnetars are believed to form the collapse of massive stars’ iron cores in core-collapse supernovae

There are many challenges scientists faced in order to example the origin of magnetar magnetic fields

CEA Saclay and Max Planck institute for Astrophysics; describes the study’s approach to developing a detailed computer model explaining the creation of strong magnetic fields during the formation of rapidly rotating neutron stars

The study also mentions the dynamo effect, where the strong internal convective mass flows during the newborn neutron star’s cooling strengthen pre-existing weak magnetic fields

The simulation highlighted the use of supercomputer to simulate convection in a rapidly spinning neutron star

The study finds that weak initial magnetic fields can be improved to extremely high values for sufficiently fast rotation periods

The study’s results also provide insights into the formation of galactic magnetars and contribute to understanding powerful stellar explosions

Additionally connects the study’s findings to the “millisecond magnetar” scenario, suggesting the rotational energy of a fast-rotating neutron star as an extra source of energy storage.

Describes how a powerful magnetic field with two poles can move the rotating energy of the neutron star into the explosion

The study’s results provide theoretical support for the millisecond magnetar scenario, addressing the main reason for extreme stellar events.

Next Question:

How does the study change our ideas about stellar evolution, especially after understanding how magnetic fields play a role in shaping objects like neutron stars in the universe?

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EarthSky | Updates on your cosmos and world

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Magnetic magnetars

Can you imagine a magnet so powerful that it could wipe every credit card on Earth from a distance halfway to the moon? That is how strong the magnetic field of a magnetar is! A magnetar is an exotic type of neutron star, its defining feature that it has an ultra-powerful magnetic field. The field is about 1,000 times stronger than a normal neutron star and about a trillion times stronger than the Earth's.

Magnetars are, by far, the most magnetic stars in the universe. If you were to venture closer to a magnetar than about 600 miles (1,000 km), you would die very quickly. Its magnetic field would destroy your body, tearing away electrons from your atoms and converting you into a cloud of monatomic ions, that is, single atoms without electrons.

A magnetar is extreme in many ways

Apart from these ultra-powerful magnetic fields, magnetars also release vast amounts of energy in the form of flares, X-rays, and gamma-ray bursts. They are therefore associated with extreme events in the universe, making them perhaps the most bizarre objects in the cosmos next to black holes.

As an example of extreme behavior, in 2004 a flare on the surface of a magnetar compressed the magnetic field of the Earth ... from a distance of 50,000 light years! When you consider that a neutron star is about the size of a city - a recent revision of neutron star size puts it at maximum of 15 miles (24 km) across - but may contain 1 1/2 times the mass of our sun, it is incredible that a such a tiny object can generate enough energy to affect others at such a vast distance.

What gives a magnetar its magnetism?

Astrophysicists do not yet know exactly how a magnetar generates its stupendous magnetic field. However, it probably relates to the incredible density of neutron stars and their bizarre interiors. Just one sugar cube-sized amount of neutron star material would weigh a billion tons on the Earth ... about the same as an average mountain!

The magnetic field of a magnetar may be caused by a neutron star's interior - thought to be made up of neutrons, quarks and exotic states of matter such as Bose-Einstein Condensates - becoming a superconducting fluid. Thus, when the star rotates, it would behave like a huge dynamo, generating an immense magnetic field.

Or, the field may simply have its origins in its progenitor star - the kind of star it was before it become a neutron star - which may have had an unusually strong magnetic field.

In an effort to solve this enigma, astronomers launched an instrument called the Neutron Star Interior Composition Explorer ( NICER) to the International Space Station in 2017. Its specific goal is to determine what exactly is inside neutron stars.

So far, NICER has enabled astronomers to make more accurate measurements regarding size and density parameters of these strange cosmic beasts.

We also stand to learn more about neutron stars from the gravitational waves they generate when two of them collide, such as in the famous gravitational-wave event GW170817.

Cosmic lighthouses

A few magnetars are also pulsars, those celestial lighthouses that sweep the sky with powerful radio beams (and, rarely, beams of visible light too, such as in the case of the Crab Nebula). Recently, detecting a magnetar that is also a pulsar enabled astronomers to establish an accurate distance to a magnetar for the first time.

First magnetar detection a mystery

The first event that originated from a magnetar showed up in 1979, although at that time astronomers did not identify the activity as belonging to a separate class of objects. It occurred when two Russian spacecraft suddenly observed a huge blast of gamma radiation in their detectors: readings on both the probes went up from a normal 100 counts per second to over 200,000 counts a second, in a fraction of a millisecond. This was more than a hundred times the energy of any extrasolar gamma-ray burst previously detected. Five satellites and two observatories also registered it, as the wave of gamma radiation traveled through the solar system.

When astronomers tracked down where the burst had originated, it corresponded to the location of a known supernova in the Large Magellanic Cloud. The object that generated this huge wave of gamma radiation has since repeated the event, making it the first known soft gamma repeater.

Nobody knew the exact cause of the event back in 1979. It wasn't until 2008 that astronomers identified a neutron star that acted like a pulsar and emitted magnetically-powered bursts. This event confirmed magnetars to be a rare type of neutron star. There are only 31 confirmed magnetars in total (as of March 2020), out of around 3,000 known neutron stars. This is an indication of their rarity.

Are magnetars responsible for fast radio bursts?

Magnetars have also emerged as prime candidates for causing Fast Radio Bursts, or FRBs, those enigmatic millisecond-long pulses of radio waves that carry as much energy as our sun releases in a year! Up until recently, astronomers thought all FRBs were extragalactic in nature, but in April 2020, they detected an FRB coming from inside our own Milky Way galaxy. Astronomers pinned its location down to a known magnetar, SGR 1935+2154.

In May 2021, NASA reported that the Hubble Space Telescope had identified four FRBs in the spiral arms of distant galaxies. These are thought to have originated from magnetars. This was an important step forward, as up until recently the exact location of FRBs proved very difficult to pin down, mostly due to their short duration of just a thousandth of a second. Furthermore, most FRBs do not repeat, making their location on the sky and distance difficult to identify.

How and why a magnetar might generate an FRB is not yet known.

Magnetars are strange denizens of the cosmic zoo, generating almost incomprehensible amounts of energy that can be detected across the universe. Just what creates their humongous magnetic fields and their immense bursts of energy across the electromagnetic spectrum is not yet known, but is an area of much active research. It seems the universe still has much to show us in the way of the unexpected and the bizarre.

Bottom line: Magnetars are a special kind of neutron star, harboring intensely strong magnetic fields. Read more about them here!

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Can you imagine a magnet so powerful that it could wipe every credit card on Earth from a distance halfway to the moon? That is how strong the magnetic field of a magnetar is! A magnetar is an exotic type of neutron star, its defining feature that it has an ultra-powerful magnetic field.

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What do hot gases have to do with black holes 

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What do hot gases have to do with black holes 

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Black holes can only be detected by observing their effects on nearby matter and space

Because of their enormous mass, black holes have extremely high gravity which pulls in surrounding material at rapid speed

This speed causes the matter to become so incredibly hot that it emits x-rays

These x-rays help us use specialized telescopes to image the materials as they spiral into the black hole, revealing the black hole’s location

This technique in used in NASA’s Chandra X-ray observatory

Other telescopes can measure the speed of the gas and start orbiting what they believe to be a black hole, then with these measurements, Scientists can determine the mass of the black hole

This is used by NASA's Hubble telescope

These two telescope are also able to image the the effects of gravitational lenseing

Gravitational lenseing is the bending of light that results from the gravitational pull of high mass objects like Galaxies and black holes

Next Questions:

What types of gases surround the black holes? Can they all be measured?

If other high mass objects like galaxies have a similar effect on light, how can we differentiate them from black holes?

Which telescope is better at identifying black holes, Chandra or Hubble?

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Find out how scientists captured the first image of Sagittarius A*, why it's important, and how to turn it into a learning opportunity for students.

Our home galaxy, the Milky Way, has a supermassive black hole at its center, but we've never actually seen it - until now. The Event Horizon Telescope, funded by the National Science Foundation, has released the first image of our galactic black hole, Sagittarius A* (pronounced "Sagittarius A-star" and abbreviated Sgr A*).

Read on to find out how the image was acquired and learn more about black holes and Sagittarius A*. Then, explore resources to engage learners in the exciting topic of black holes.

How Black Holes Work

A black hole is a location in space with a gravitational pull so strong that nothing, not even light, can escape it. A black hole's outer edge, called its event horizon, defines the spherical boundary where the velocity needed to escape exceeds the speed of light. Matter and radiation fall in, but they can't get out. Because not even light can escape, a black hole is literally black. Contrary to their name's implication, black holes are not empty. In fact, a black hole contains a great amount of matter packed into a relatively small space. Black holes come in various sizes and can exist throughout space.

We can surmise a lot about the origin of black holes from their size. Scientists know how some types of black holes form, yet the formation of others is a mystery. There are three different types of black holes, categorized by their size: stellar-mass, intermediate-mass, and supermassive black holes.

Stellar-mass black holes are found throughout our Milky Way galaxy and have masses less than about 100 times that of our Sun. They comprise one of the possible endpoints of the lives of high-mass stars. Stars are fueled by the nuclear fusion of hydrogen, which forms helium and other elements deep in their interiors. The outflow of energy from the central regions of the star provides the pressure necessary to keep the star from collapsing under its own weight.

Once the fuel in the core of a high-mass star has completely burned out, the star collapses, sometimes producing a supernova explosion that releases an enormous amount of energy, detectable across the electromagnetic spectrum. If the star's mass is more than about 25 times that of our Sun, a stellar-mass black hole can form.

Intermediate-mass black holes have masses between about 100 and 100,000 times that of our Sun. Until recently, the existence of intermediate-mass black holes had only been theorized. NASA's Chandra X-ray Observatory has identified several intermediate-mass black hole candidates by observing X-rays emitted by the gas surrounding the black hole. The Laser Interferometer Gravitational Wave Observatory, or LIGO, funded by the National Science Foundation, detected the merger of two stellar-mass black holes with masses 65 and 85 times that of our Sun forming an intermediate-mass black hole of 142 solar masses. (Some of the mass was converted to energy and about nine solar masses were radiated away as gravitational waves.)

Supermassive black holes contain between a million and a billion times as much mass as a stellar-mass black hole. Scientists are uncertain how supermassive black holes form, but one theory is that they result from the combining of stellar-mass black holes.

Our local galactic center's black hole, Sagittarius A*, is a supermassive black hole with a mass of about four million suns, which is fairly small for a supermassive black hole. NASA's Hubble Space Telescope and other telescopes have determined that many galaxies have supermassive black holes at their center.

Why They're Important

Black holes hold allure for everyone from young children to professional astronomers. For astronomers, in particular, learning about Sagittarius A* is important because it provides insights into the formation of our galaxy and black holes themselves.

Understanding the physics of black hole formation and growth, as well as their surrounding environments, gives us a window into the evolution of galaxies. Though Sagittarius A* is more than 26,000 light years (152 quadrillion miles) away from Earth, it is our closest supermassive black hole. Its formation and physical processes influence our galaxy as galactic matter continually crosses the event horizon, growing the black hole's mass.

Studying black holes also helps us further understand how space and time interact. As one gets closer to a black hole, the flow of time slows down compared with the flow of time far from the black hole. In fact, according to Einstein's theory of general relativity, the flow of time slows near any massive object. But it takes an incredibly massive object, such as a black hole, to make an appreciable difference in the flow of time. There's still much to learn about what happens to time and space inside a black hole, so the more we study them, the more we can learn.

How Scientists Imaged Sagittarius A*

Black holes, though invisible to the human eye, can be detected by observing their effects on nearby space and matter. As a result of their enormous mass, black holes have extremely high gravity, which pulls in surrounding material at rapid speeds, causing this material to become very hot and emit X-rays.

X-ray-detecting telescopes such as NASA's Chandra X-ray Observatory can image the material spiraling into a black hole, revealing the black hole's location. NASA's Hubble Space Telescope can measure the speed of the gas and stars orbiting a point in space that may be a black hole. Scientists use these measurements of speed to determine the mass of the black hole. Hubble and Chandra are also able to image the effects of gravitational lensing, or the bending of light that results from the gravitational pull of black holes or other high-mass objects such as galaxies.

To directly image the matter surrounding a black hole, thus revealing the silhouette of the black hole itself, scientists from around the world collaborated to create the Event Horizon Telescope. The Event Horizon Telescope harnesses the combined power of numerous telescopes around the world that can detect radio-wave emissions from the sky to create a virtual telescope the size of Earth.

In 2019, the team released the first image of a black hole's silhouette when they captured the glowing gasses surrounding the M87* galactic black hole nearly 53 million light-years (318 quintillion miles) away from Earth. The team then announced that one of their next endeavors was to image Sagittarius A*.

To make the newest observation, the Event Horizon Telescope focused its array of observing platforms on the center of the Milky Way. A telescope array is a group of telescopes arranged so that, as a set, they function similarly to one giant telescope. In addition to the telescopes used to acquire the M87* image, three additional radio telescopes joined the array to acquire the image of Sagittarius A*: the Greenland Telescope, the Kitt Peak 12-meter Telescope in Arizona, and the NOrthern Extended Millimeter Array, or NOEMA, in France.

The distance from the center of Sagittarius A* to its event horizon, a measurement known as the Schwarzschild radius, is enormous at seven million miles (12,000,000 kilometers or 0.08 astronomical units). But its apparent size when viewed from Earth is tiny because it is so far away. The apparent Schwarzschild radius for Sagittarius A* is 10 microarcseconds, about the angular size of a large blueberry on the Moon.

Acquiring a good image of a large object that appears tiny when viewed from Earth requires a telescope with extraordinarily fine resolution, or the ability to detect the smallest possible details in an image. The better the resolution, the better the image and the more detail the image will show. Even the best individual telescopes or array of telescopes at one location do not have a good enough resolution to image Sagittarius A*.

The addition of the 12-meter Greenland Telescope, though a relatively small instrument, widened the diameter, or aperture, of the Event Horizon Telescope to nearly the diameter of Earth. And NOEMA - itself an array of twelve 15-meter antennas with maximum separation of 2,500 feet (760 meters) - helped further increase the Event Horizon Telescope's light-gathering capacity.

Altogether, when combined into the mighty Event Horizon Telescope, the virtual array obtained an image of Sagittarius A* spanning about 50 microarcseconds, or about 1/13th of a billionth the span of the night sky.

While the Event Horizon Telescope was busy capturing the stunning radio image of Sagittarius A*, an additional worldwide contingent of astronomical observatories was also focused on the black hole and the region surrounding it. The aim of the team, known as the Event Horizon Telescope Multiwavelength Science Working Group, was to observe the black hole in other parts of the electromagnetic spectrum beyond radio. As part of the effort, X-ray data were collected by NASA's Chandra X-ray Observatory, Nuclear Spectroscopic Telescope (NuSTAR), and Neil Gehrels Swift Observatory, additional radio data were collected by the East Asian Very Long-Baseline Interferometer (VLBI) network and the Global 3 millimeter VLBI array, and infrared data were collected by the European Southern Observatory's Very Large Telescope.

The data from these multiple platforms will allow scientists to continue building their understanding of the behavior of Sagittarius A* and to refine their models of black holes in general. The data collected from these multiwavelength observations are crucial to the study of black holes, such as the Chandra data revealing how quickly material falls in toward the disk of hot gas orbiting the black hole's event horizon. Data such as these will hopefully help scientists better understand black hole accretion, or the process by which black holes grow.

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This Teachable Moment was created in partnership with NASA's Universe of Learning. Universe of Learning materials are based upon work supported by NASA under award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Center for Astrophysics | Harvard & Smithsonian, and the Jet Propulsion Laboratory. TAGS: Black hole, Milky Way, galaxy, universe, stars, teachers, educators, lessons, Teachable Moments, K-12, science

Ota Lutz, K-12 Education Group Manager, NASA-JPL Education Office

Ota Lutz is the manager of the K-12 Education Group at NASA's Jet Propulsion Laboratory. When she's not writing new lessons or teaching, she's probably cooking something delicious, volunteering in the community, or dreaming about where she will travel next.

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Telescopes Get Extraordinary View of Milky Way's Black Hole - Teachable Moments | NASA/JPL Edu

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Find out how scientists captured the first image of Sagittarius A*, why it's important, and how to turn it into a learning opportunity for students.

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What types of gases surround the black holes? Can they all be measured?

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What types of gases surround the black holes? Can they all be measured?

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Scientists making use of the James Web Telescope began to study a certain aspect of several different galaxies called the active galactic nucleus, which is meant to describe the supermassive black hole at the center of a galaxy. This process was conducted using a specialized observation tool called a “Medium-Resolution Spectrometer”, or MRS for short which in turn is a part of another observation tool called the “Mid-Infrared Instrument”, or MIRI for short.

This specialized spectrometer utilizes another concept called integral field units, or IFUs for short, these units are a combination of both a camera and a spectrograph, a spectrograph being a specialized tool allowing scientists to discover properties of a material depending on how light interacts with it. This special field unit is used to provide the team working with the James Webb Telescope with a database of images of their goal, the features of a galactic core black hole.

One featured use of IFUs is for scientists to collect large amounts of spectral data on a structure, this including measurements and even velocity.

Using the previously mentioned tools, the MRS of the MIRI, scientists are able to see through the clouds of dust that surround this core black hole and analyze the contents behind these clouds. What specifically is being measured during this viewing is emissions caused by the very hot gases surrounding the black hole, these gases become very bright as a result of being ionized by powerful winds and radiation emanating from the black hole.

The process of how these dust clouds come to be is due to the black hole’s outflowing wind, which is incredibly hot and easily pushes a great deal of material away from the black hole itself, hence creating surrounding clouds.

MIRI was able to determine this by looking into several regions of the black hole and discovered circles of material at varying distances from the black hole. The final result of what made up these clouds of dust was very finely-grained silica dust, a relatively similar makeup to beach sand

This specific viewing of a core black hole was able to capture its contents in a precision never seen before, therefore being able to determine the composition of these surrounding gases, which was divided into two known spectrums

The top spectrum contained various gases that had become ionized and very warm, such as iron, argon, oxygen, neon, and sulphur.

On the other hand, the bottom spectrum contained much colder and very denser gases, which were mainly composed of molecular hydrogen and once again, silicate dust.

Further Questions:

What is the main purpose behind all these very specialized tools?

Just how many tools like MIRI exist for studying black holes?

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How to calculate the mass of a black hole?

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How to calculate the mass of a black hole?

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As we know, a black hole is not directly visible to the naked eye

In order to “see” them we must observe surrounding objects like stars or other planets orbiting it

In the case of calculating the mass of a black hole, we use the same observations except to a deeper lever

When the black hole and another star are in the same orbit around a mutual center of gravity, using accurate observations we are capable of measuring the speed and the distance of the stars orbit

Using these factors we are then able to excel determine the mass of the black hole using laws of gravity

For example, let's assume that there is a star like the sun orbiting a black hole and the star is traveling at 117 miles per second

then we detect that the orbit is very similar to the planet mercury, meaning that the sun orbits the black hole once every 12 days

The laws of gravity then tell us that the mass of the black hole must be 10 times larger than the star

Further question:

How do we determine the speed of a black hole's orbit?

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JavaScript must be installed and turned on in your browser to view content on most pages of this site, including Journey to a Black hole. If you experience other problems, verify that your setup matches the Technical Requirements for this site.

Black holes often have stars or gas orbiting around them. It is then possible to measure the mass of the black hole, just by measuring the speed of the orbiting material.

Consider the case in which a star and a black hole orbit around their mutual center of gravity. Although we can't see the black hole, we can see the star. With accurate observations, we can measure the speed of the star as well as the size of the orbit. Once these have been measured, the laws of gravity tell us exactly what the black hole mass is.

For example, let's assume that a star like our Sun orbits a black hole. Suppose that we measure the speed of the star to be 117 miles per second, and that we measure the diameter of its orbit to be similar to the distance of the planet Mercury from our Sun. This implies that the star orbits the black hole once every 12 days. The laws of gravity then tell us that the black hole must be 10 times more massive than our Sun.

The supermassive black holes in the centers of galaxies can often be measured using this method. For example, the mass of the black hole in the center of our Milky Way galaxy was calculated by measuring the speeds of individual stars that orbit around it. This showed that the black hole is three million times more massive than our Sun. And the mass of the black hole in the center of the nearby Andromeda galaxy has been calculated by measuring the average speeds of all the stars that orbit around it. This showed that Andromeda's black hole is 30 million times more massive than our Sun. The following pages provide more details about these galaxies and their supermassive black holes:

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HubbleSite: Black Holes: Gravity's Relentless Pull interactive: About This Site: Encyclopedia

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JavaScript must be installed and turned on in your browser to view content on most pages of this site, including Journey to a Black hole. If you experience other problems, verify that your setup matches the Technical Requirements for this site. Black holes often have stars or gas orbiting around them.

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What kind of gases surround black holes and how do we detect them?

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What kind of gases surround black holes and how do we detect them?

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Black holes are surrounded by a region called the accretion disc and it is composed of many different gas and dust particles, as well as any other matter that was pulled towards the black hole by gravity

When all these materials sin towards the black hole, it creates a hot and dense disc because of gravitational forces

Usually you will be able to find elements such as hydrogen, helium, and some other heavier elements

Sometimes when this disc becomes extremely hot, the elements become ionized, then forming plasma

In order to determine what material is found around the black hole, we can use x-rays

X-rays are produced in extremely hot and energetic environments, such as the accretion disc

On earth, we can use instruments such as x-ray telescopes, such as Chandra X observatory that are specifically created to capture and analyze x-rays from celestial objects

These x-ray signals in the accretion disc provide information of the composition of the element inside

Further question:

What caused matter to collect on the accretion disk?

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How do we determine the speed of a black hole's orbit.

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How do we determine the speed of a black hole's orbit.

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Black holes are incredibly immense objects that due to their large gravity, have the power to distort and even twist the space-time of the universe around them. But it is a result of this power that we can observe them in a way, as due to these distortions of space-time, black holes go so far as to bend the very light around them. Using the bending of light, researchers are able to gain several insights about black holes, this including the rate at which black holes spin.

There are currently three known ways in which a black hole spins:

Retrograde spin: where the accretion disk of the black hole (its circle of matter surrounding it) is found moving in the opposite direction of the black hole

Prograde spin: where the accretion disk of the black hole is found moving in the same direction of the black hole

Finally, no spin: where the black hole is not found to be spinning at all

As for the method in which one of these three spin methods is detected, scientists then begin to rely on the accretion disk, which is a phenomenon once again caused by the fact that a black hole has the ability to bend light. Scientists observe the accretion disk as the faster a black hole moves, the closer its accretion disk will be to its center.

Scientists observe the accretion disk of the black hole as they have methods to extract the necessary information from it. They begin by assessing the X-ray light emanating from the accretion disk into an entire spectrum of different qualities, including mainly colours and energies.

One observation that can be easily made about the accretion disk is iron atoms scattered about in the accretion disk. If the accretion disk is found to be very close to the black hole, the colours found on the spectrum from the X-ray light will be largely spread out, as a result of the incredibly large gravitational pull closer to the black hole.

Therefore by using the degree to which the iron was found to be scattered around the accretion disk, scientists are then able to find how close the accretion disk will be positioned to the black hole. Then by using the aforementioned fact that the speed of a black hole is proportional to the closeness of its accretion disk, scientists can determine the rate at which a black hole spins

Further Question:

Why is it specifically iron that is able to give scientists these observations? What makes iron special in this scenario?

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Black holes are tremendous objects whose immense gravity can distort and twist space-time, the fabric that shapes our universe. These effects, consequences of Einstein's general theory of relativity, result in the bending of light as it travels through space-time. By looking for these light distortions in X-rays streaming off material near black holes, researchers can gain information about their spin rates.
This chart illustrates the basic model for determining the spin rates of black holes. The three artist's concepts represent the different types of spin: retrograde rotation, where the disk of matter falling onto the hole, called an accretion disk, moves in the opposite direction of the black hole; no spin; and prograde rotation, where the disk spins in the same direction as the black hole.
The faster a black hole spins, the closer its accretion disk can lie to it - another consequence of Einstein's theory of relativity.
Scientists assess how close the inner edge of an accretion disk comes to a black hole by breaking the X-ray light up into a spectrum of different colors, or energies. The resulting spectra for the three spin scenarios are shown at right. The sharp peak is X-ray radiation from iron atoms circulating in the accretion disk. If the accretion disk is close to the black hole, as is the case in the final row, the X-ray colors from the iron will be spread out by the immense gravity of the black hole. The degree to which the iron feature is spread out, a phenomenon referred to as the "red wing," reveals how close the accretion disk is to the black hole. Because this distance depends on the black hole's spin, the spin rate can then be determined.
Prior to observations with NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), which captures X-ray radiation with energy from the 3 to 79 kiloelectron volt (keV) range, this model remained uncertain. Together with the European Space Agency's XMM-Newton telescope, which sees X-ray light in the 0.1 to 10 keV range, the observatories were able to show that the model is correct. Their data ruled out the possibility that the iron feature only appears to be distorted as a result of intervening absorbing clouds, and not gravitational effects.
Image credit: NASA/JPL-Caltech

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How to Measure the Spin of a Black Hole - NASA

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Black holes are tremendous objects whose immense gravity can distort and twist space-time, the fabric that shapes our universe. These effects, consequences of Einstein's general theory of relativity, result in the bending of light as it travels through space-time.