Astronomy

Blackhole Finding Techniques

Blackhole Finding Techniques


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I know of two methods for finding exoplanets: the transit method and the radial velocity method. These two methods work as follows:

  1. Transit: we observe stars and watch for when a planet obstructs the light from the star.

  2. Radial Velocity: detecting the planet by observing the motion of the star and using Kepler's law.

Are these methods also used for discovering black-holes? What are the pros and cons of these methods, I think that the con of transit is that it's difficult to see the black hole. A pro is that it doesn't matter how many stars there are around the black hole.

With the Radial Velocity method, a pro is that it's easy to detect but requires exactly one companion star (I used this source).


We detect black holes mostly by their effects on nearby matter. The "radial velocity" method is important after x-ray observations suggest a likely black-hole.

Matter in orbit around a black hole can form an accretion disc. This disc will become very hot, and glow brightly in X-ray radiation. If we see X-ray radiation coming from a star we look at the radial velocity of the star, and use this to infer the mass of the orbiting object. Since a neutron star cannot exist at more than 3 solar masses, if the object is more than that it must be a black hole.

Compared to planets, black holes are rare. Only about 20 candidates are known in the Milky way.


Astronomers amazed to find supermassive black hole wandering aimlessly through space

Supermassive black holes generally stay put as they suck in everything that comes their way, but scientists have long thought it was possible for them to wander through space. They've just never properly caught one in the act &mdash until now.

Researchers and the Center for Astrophysics | Harvard & Smithsonian have identified the clearest example yet of a black hole in motion, publishing their findings in The Astrophysical Journal. About 230 million light years away, at the center of a galaxy named J0437+2456, the team found what they were looking for.

"We don't expect the majority of supermassive black holes to be moving they're usually content to just sit around," lead author Dominic Pesce said in a news release. "They're just so heavy that it's tough to get them going. Consider how much more difficult it is to kick a bowling ball into motion than it is to kick a soccer ball &mdash realizing that in this case, the 'bowling ball' is several million times the mass of our Sun. That's going to require a pretty mighty kick."

The team has been studying 10 distant galaxies and their supermassive black holes, specifically ones containing water, for the past five years. They were able to precisely measure a black hole's velocity based on the water orbiting the black hole, which produces a measurable laser-like beam of radio light, known as a "maser."

"We asked: Are the velocities of the black holes the same as the velocities of the galaxies they reside in?" Pesce explained. "We expect them to have the same velocity. If they don't, that implies the black hole has been disturbed."

Galaxy J0437+2456 is thought to be home to a supermassive, moving black hole. Sloan Digital Sky Survey

Nine of the 10 black holes were resting &mdash but one appeared to be in motion.

Space & Astronomy

Follow-up observations with the Arecibo Observatory in Puerto Rico, before its collapse, and the Gemini Observatory in Hawaii and Chile confirmed the findings: The black hole, which has a mass that is 3 million times that of our sun, is moving at about 110,000 miles per hour inside its galaxy.

Scientists have two theories for the wandering black hole. One possibility? A collision.

"We may be observing the aftermath of two supermassive black holes merging," said co-author Jim Condon. "The result of such a merger can cause the newborn black hole to recoil, and we may be watching it in the act of recoiling or as it settles down again."

Scientists also think it's possible that the black hole is part of a pair.

"Despite every expectation that they really ought to be out there in some abundance, scientists have had a hard time identifying clear examples of binary supermassive black holes," Pesce says. "What we could be seeing in the galaxy J0437+2456 is one of the black holes in such a pair, with the other remaining hidden to our radio observations because of its lack of maser emission."

More observations are needed to understand the true cause of the peculiar movement.

First published on March 16, 2021 / 11:30 AM

© 2021 CBS Interactive Inc. All Rights Reserved.

Sophie Lewis is a social media producer and trending writer for CBS News, focusing on space and climate change.


Reliable way to find a black hole in expeditions? Nada and Polo have not been helpful

I've done most of the expeditions tasks and I'm starting to worry that after all the time I've invested in that golden vector I won't actually be able to get it because I'm not finding any black holes! When I select the expeditions quest for it, it shows up in my quest log with the text

Find Nada on the Space Anomaly for assistance. Once marked, the black hole will appear as a route option on the Galaxy Map.

But Nada isn't telling me anything about black holes and neither is Polo, so that might be a bug. Also, when I exit the menu after selecting the quest, the little quest pop-up in the bottom right corner says

So this looks like the name of a string constant or something, not very helpful! (Not sure if this bug is known and has been reported to HG yet?) I can't select it as a "current mission" on the galaxy map either.

So I'm wondering if there is a reliable way to find a black hole without Nada and Polo's help? Should I just keep jumping to different systems and hope for the best? I've read somewhere on here that some space anomalies count as black holes, should I repeatedly use my anomaly detectors, quit and reload until I find the right anomaly? It all feels quite dependant on RNG, so Iɽ appreciate any tips to make this less grindy. Thank you!

Edit: Turns out flying through a relic gate doesn't count towards the expeditions milestone.

Edit 2: I've submitted a bug report to HG, hopefully they'll fix it before the end of this expeditions season so I won't have to randomly jump between systems hoping to eventually find a black hole.

Edit 3: It looks like there is a reliable black hole in Osenti, very close to the starting system! It's in the opposite direction to the expedition path, a screenshot of the galaxy map is here: https://imgur.com/a/HhhAfn5

Edit 4: Osenti coordinates uploaded here by /u/alehost : https://imgur.com/a/gRdxor6 Name of the system was originally correctly remembered by /u/LumenNoctis90 . Finding this workaround felt like a proper team effort, almost in the sense of a. community expedition? Though I'm pretty sure teaming up to find ways around the bugs wasn't quite what Hello Games had in mind with this new game mode!

Edit 5: More info about Osenti: it's a yellow system with a Gek population, and both its economy and conflict are at level 2.

Edit 6: More info provided by /u/Brain5torm : the distance between Loytkara and Osenti is 169LY.


Evidence of supermassive galactic drama

In results recently published in the Astrophysical Journal, they confirmed that the host galaxy does indeed appear to be moving independently of its central black hole. Other astronomers have found candidates for supermassive black holes on the move (including one spotted in 2017 cruising at a blistering 4.7 million miles per hour), but this example is the “most concrete case” yet, according to Pesce.

Since it takes a supermassive black hole to move a supermassive black hole, the researchers believe that this object must have been dislodged by a partner during a mashup with a neighboring galaxy. Certain regions of the host galaxy also appear to be moving in funky ways, supporting the idea that some galactic drama has gone down relatively recently.

What the team doesn’t yet know is what stage of the rendezvous the supermassive black hole is in. It could be blazing a path toward its counterpart. It could be locked into a spiral with its partner. Or the merger could be over, and the newly forged composite black hole could be rocketing away from the site of the collision.

Other astronomers find the evidence for a roaming black hole compelling, but point out that without knowing more about which way it’s going, this observation doesn’t prove that supermassive black holes can definitely grow by colliding.

“The authors present a very promising object, although I am not sure it is the best case overall,” wrote Marco Chiaberge, an astronomer at the Space Telescope Science Institute in Baltimore, who helped discover the super-speedy supermassive black hole candidate in 2017, in an email. “There is still the possibility that the black hole is ‘on its way to the center,’ meaning that the black hole merger has not happened yet.”

With additional observations, the researchers hope, they’ll be able to figure out exactly what’s going on.

“To me, the most exciting scenario would be if [the galaxy] turns out to be hosting a binary black hole system,” Pesce says, because very few such pairs are known to astronomers. “And of course,” he adds, “two black holes are twice as exciting as one.”

Charlie Woodis a journalist covering developments in the physical sciences both on and off the planet. In addition to Popular Science, his work has appeared in Quanta Magazine, Scientific American, The Christian Science Monitor, and other publications. Previously, he taught physics and English in Mozambique and Japan, and studied physics at Brown University. You can view his website here.


A Collision in Space Caused a Black Hole 142 Times Bigger Than the Sun

The collision is believed to have happened about 7 billion years ago.

According to PBS, scientists have observed the collision of two black holes, creating a new size of black hole that has never been seen before.

Rest assured, this massive black hole won’t be consuming our universe like it would in a sci-fi movie. This black hole collision is thought to have occurred over seven billion years ago, and we are just observing it now because it is so far away, according to PBS.

Before this new type of black hole was seen, scientists thought that were only two basic sizes of black holes, PBS reported. The first, smaller sized, caused by a star that dies and collapses in on itself — also known as a stellar black hole — and a larger sized, supermassive black hole that&aposs millions of times larger than Earth’s sun and have complete galaxies that revolve around them. This recently observed black hole is somewhere between the two, according to PBS.

The event was observed in May 2019, when scientists picked up a signal that turned out to be two stellar black holes colliding with each other. The two black holes were 66 times and 85 times the mass of Earth’s sun, PBS reported, resulting in a black hole that was around 142 times bigger than the sun. While you might think this collision would be absolutely deafening to hear, the signal was actually pretty tame.

“It just sounds like a thud,” said Caltech physicist Alan Weinstein to PBS. “It really doesn’t sound like much on a speaker.” Despite the rather anticlimactic sound, the collision is thought to be the 𠇋iggest bang since the Big Bang observed by humanity,” according to Weinstein.

It’s currently not known how supermassive black holes form (or grow in size, for that matter), but the observance of events such as this can provide more information for further study. In fact, a black hole was only first photographed back in April 2019.


To find giant black holes, start with Jupiter

On a quest to find the Universe's largest black holes, Vanderbilt researcher identifies the center of the solar system within 100 meters. Credit: David Champion

The revolution in our understanding of the night sky and our place in the universe began when we transitioned from using the naked eye to a telescope in 1609. Four centuries later, scientists are experiencing a similar transition in their knowledge of black holes by searching for gravitational waves.

In the search for previously undetected black holes that are billions of times more massive than the sun, Stephen Taylor, assistant professor of physics and astronomy and former astronomer at NASA's Jet Propulsion Laboratory (JPL) together with the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration has moved the field of research forward by finding the precise location—the center of gravity of our solar system—with which to measure the gravitational waves that signal the existence of these black holes.

The potential presented by this advancement, co-authored by Taylor, was published in the journal the Astrophysical Journal in April 2020.

Black holes are regions of pure gravity formed from extremely warped spacetime. Finding the most titanic black holes in the Universe that lurk at the heart of galaxies will help us understand how such galaxies (including our own) have grown and evolved over the billions of years since their formation. These black holes are also unrivaled laboratories for testing fundamental assumptions about physics.

Gravitational waves are ripples in spacetime predicted by Einstein's general theory of relativity. When black holes orbit each other in pairs, they radiate gravitational waves that deform spacetime, stretching and squeezing space. Gravitational waves were first detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2015, opening new vistas on the most extreme objects in the universe. Whereas LIGO observes relatively short gravitational waves by looking for changes in the shape of a 4-km long detector, NANOGrav, a National Science Foundation (NSF) Physics Frontiers Center, looks for changes in the shape of our entire galaxy.

Taylor and his team are searching for changes to the arrival rate of regular flashes of radio waves from pulsars. These pulsars are rapidly spinning neutron stars, some going as fast as a kitchen blender. They also send out beams of radio waves, appearing like interstellar lighthouses when these beams sweep over Earth. Over 15 years of data have shown that these pulsars are extremely reliable in their pulse arrival rates, acting as outstanding galactic clocks. Any timing deviations that are correlated across lots of these pulsars could signal the influence of gravitational waves warping our galaxy.

On a quest to find the Universe's largest black holes, Vanderbilt researcher identifies the center of the solar system within 100 meters. Credit: Tonia Klein/NANOGrav Physics Frontier Center

"Using the pulsars we observe across the Milky Way galaxy, we are trying to be like a spider sitting in stillness in the middle of her web," explains Taylor. "How well we understand the solar system barycenter is critical as we attempt to sense even the smallest tingle to the web." The solar system barycenter, its center of gravity, is the location where the masses of all planets, moons, and asteroids balance out.

Where is the center of our web, the location of absolute stillness in our solar system? Not in the center of the sun as many might assume, rather it is closer to the surface of the star. This is due to Jupiter's mass and our imperfect knowledge of its orbit. It takes 12 years for Jupiter to orbit the sun, just shy of the 15 years that NANOGrav has been collecting data. JPL's Galileo probe (named for the famed scientist that used a telescope to observe the moons of Jupiter) studied Jupiter between 1995 and 2003, but experienced technical maladies that impacted the quality of the measurements taken during the mission.

Identifying the center of the solar system's gravity has long been calculated with data from Doppler tracking to get an estimate of the location and trajectories of bodies orbiting the sun. "The catch is that errors in the masses and orbits will translate to pulsar-timing artifacts that may well look like gravitational waves," explains JPL astronomer and co-author Joe Simon.

Taylor and his collaborators were finding that working with existing solar system models to analyze NANOGrav data gave inconsistent results. "We weren't detecting anything significant in our gravitational wave searches between solar system models, but we were getting large systematic differences in our calculations," notes JPL astronomer and the paper's lead author Michele Vallisneri. "Typically, more data delivers a more precise result, but there was always an offset in our calculations."

The group decided to search for the center of gravity of the solar system at the same time as sleuthing for gravitational waves. The researchers got more robust answers to finding gravitational waves and were able to more accurately localize the center of the solar system's gravity to within 100 meters. To understand that scale, if the sun were the size of a football field, 100 meters would be the diameter of a strand of hair. "Our precise observation of pulsars scattered across the galaxy has localized ourselves in the cosmos better than we ever could before," said Taylor. "By finding gravitational waves this way, in addition to other experiments, we gain a more holistic overview of all different kinds of black holes in the Universe."

As NANOGrav continues to collect ever more abundant and precise pulsar timing data, astronomers are confident that massive black holes will show up soon and unequivocally in the data.


Pulsars, black holes, spacetime, and the search for the center of the solar system

Astronomers have figured out how to find the center of mass of the solar system. And that in turn will help them use überdense stars spinning faster than the blades on a kitchen blender to find gigantic black holes across the Universe that are eating each other.

OK, first of all, you might think the location of the center of mass of the solar system is obvious: The center of the Sun. It has 99.8% of all the mass in the solar system, after all!

But that’s not correct. If the planets had no mass, then yeah, the center of the Sun would be the center of mass. But planets do have mass, and that means their gravity pulls on the Sun as well, changing the location of the center of mass, what we call the barycenter.

Two objects of different masses orbit each other the more massive one makes a little circle and the lower mass one a bigger circle. Credit: NASA/Spaceplace

The location of that point depends on the mass of the planet and how far it is from the Sun. Jupiter dominates here, since it has the most mass of all the planets, but the other planets contribute, too. Worse, they’re all in motion, so the actual barycenter of the solar system is constantly spiraling around as well.

The way to figure out the exact location of the barycenter is to know exactly where the planets are at all times, but that’s extremely difficult to do. Even with spacecraft visiting these other planets there’s only so accurate a measurement we can make on their location, especially over time. And that, it turns out, is not enough for some kinds of scientific measurements.

What kinds? OK, a very slight digression here.

Artwork depicting two black holes orbiting each other. Note the spins don't align. Credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

When two supermassive black holes orbit each other they emit what are called gravitational waves, literally ripples in the fabric of spacetime (OK, so this is maybe more than a slight digression). These waves can be detected on Earth as extremely small distortions in distances between two objects — and I mean far smaller than the diameter of a proton, so very small. Still, gravitational wave observatories like LIGO and Virgo have succeeded in measuring them.

They detect the waves created just before and during the merger. But in the years leading up to that moment the black holes are still giving off these waves, but the frequency of the waves is much lower. Detecting those waves is much harder, but scientifically useful. So astronomers came up with a genius idea. Use millisecond pulsars.

Yeah, we’re going to need another digression.

Pulsars are superdense neutron stars, the leftover cores of massive stars that have exploded. They have ridiculously strong magnetic fields, and these can focus twin beams of energy blasting away from the neutron star. As the neutron star spins these beams sweep across space like beams from a lighthouse, and on Earth with radio telescopes we see them as regular blips, or pulses. That’s why they’re called pulsars.

Some pulsars spin incredibly rapidly, hundreds of times per second. We call these millisecond pulsars, and their pulses are fantastically regular, like the Universe’s own ticking clocks.

However, if a gravitational wave passes through the pulsar it distorts the timing of the pulse arrival at Earth, which means that in principle timing the exact arrival of these pulses can be used to measure gravitational waves! The merging black holes are literally warping the shape of our galaxy, subtly changing the distances between pulsars, and that may be detectable. Amazing.

You need a lot of pulsars distributed throughout the sky to do this, and astronomers all over the world observe about a hundred such millisecond pulsars to see if it can be done. This group is called the International Pulsar Timing Array, made up of several different groups looking at different pulsars.

But there’s a problem. As the Earth orbits the solar system’s barycenter (aha! The digressions are over and we’re back on track) it also changes the arrival time of the pulsar blips. Sometimes the Earth is closer to the pulsar, sometimes farther away, and astronomers need to compensate for that or else the timing measurements would be hopelessly off so much so that it would overwhelm the tiny change due to any gravitational waves. To be able to see gravitational waves well using all these pulsars, the solar system barycenter needs to be known to less than about 100 meters.

Current orbital calculations for the planets aren’t that accurate. Also, the ones currently used don’t typically give the uncertainties in their measurements, which is important in figuring out how far off things might be.

Artwork depicting gravitational waves distorting space, changing the way neutron star pulses arrive at Earth. Credit: David Champion

So, to help, a team of pulsar timing astronomers looked at the equations statistically. They used Bayesian statistics, which I’ve talked about before. It’s a way of using prior knowledge of the situation and including it in the math, learning from the results. By doing this they hoped to get a handle on the uncertainties in the location of the barycenter so that they could then zero in on it.

The math is a tad complex, but in the end… it worked! They were able to nail down the solar system’s barycenter to about 100 meters, and the method can be used to get much better timing on the pulsar pulses. They found the biggest influence on the math was Jupiter, and data from the Juno spacecraft will, over the next few years, hopefully allow them to better calculate its orbit to make the aim of this statistical barycenter method even better.

It may still be some time before the pulsar array can start to detect gravitational waves. Most likely what they’ll find first is the gravitational wave background the noise from all the combined black hole mergers from all over the Universe at the time (like walking into a crowded bar and hearing the noise from all the people talking at the same time before being able to pick out individual voices). But there’s important science in that as well, and this new barycenter finder will help them get to it.

Knowing how to find the center of mass of the solar system sounds mundane, but once you have it you can unlock incredible science: Using millisecond pulsars to find supermassive black holes eating each other clear across the visible Universe!

In science, nothing is mundane. It all fits together, as it must. It’s describing everything.


Unexpected Discovery: Hubble Space Telescope Uncovers Concentration of Small Black Holes

Scientists were expecting to find an intermediate-mass black hole at the heart of the globular cluster NGC 6397, but instead they found evidence of a concentration of smaller black holes lurking there. New data from the NASA/ESA Hubble Space Telescope have led to the first measurement of the extent of a collection of black holes in a core-collapsed globular cluster.

Globular clusters are extremely dense stellar systems, in which stars are packed closely together. They are also typically very old — the globular cluster that is the focus of this study, NGC 6397, is almost as old as the Universe itself. It resides 7800 light-years away, making it one of the closest globular clusters to Earth. Because of its very dense nucleus, it is known as a core-collapsed cluster.

This ancient stellar jewelry box, a globular cluster called NGC 6397, glitters with the light from hundreds of thousands of stars. Astronomers used the NASA/ESA Hubble Space Telescope to gauge the cluster’s distance at 7800 light-years away. NGC 6397 is one of the closest globular clusters to Earth. The cluster’s blue stars are near the end of their lives. These stars have used up their hydrogen fuel that makes them shine. Now they are converting helium to energy in their cores, which fuses at a higher temperature and appears blue. The reddish glow is from red giant stars that have consumed their hydrogen fuel and have expanded in size. The myriad small white objects include stars like our Sun. This image is composed of a series of observations taken from July 2004 to June 2005 with Hubble’s Advanced Camera for Surveys. The research team used Hubble’s Wide Field Camera 3 to measure the distance to the cluster. Credit: NASA, ESA, and T. Brown and S. Casertano (STScI), Acknowledgement: NASA, ESA, and J. Anderson (STScI)

When Eduardo Vitral and Gary A. Mamon of the Institut d’Astrophysique de Paris set out to study the core of NGC 6397, they expected to find evidence for an “intermediate-mass” black hole (IMBH). These are smaller than the supermassive black holes that lie at the cores of large galaxies, but larger than stellar-mass black holes formed by the collapse of massive stars. IMBH are the long-sought “missing link” in black hole evolution and their mere existence is hotly debated, although a few candidates have been found (see [1] , for example).

Ground-based Image of Globular Cluster NGC 6397. Credit: D. Verschatse (Antilhue Observatory, Chile)

To look for the IMBH, Vitral and Mamon analyzed the positions and velocities of the cluster’s stars. They did this using previous estimates of the stars’ proper motions [2] from Hubble images of the cluster spanning several years [3] , in addition to proper motions provided by ESA’s Gaia space observatory, which precisely measures the positions, distances and motions of stars. Knowing the distance to the cluster allowed the astronomers to translate the proper motions of these stars into velocities.

“Our analysis indicated that the orbits of the stars are close to random throughout the globular cluster, rather than systematically circular or very elongated,” explained Mamon.

“We found very strong evidence for invisible mass in the dense central regions of the cluster, but we were surprised to find that this extra mass is not point-like but extended to a few percent of the size of the cluster,” added Vitral.

This invisible component could only be made up of the remnants (white dwarfs, neutron stars, and black holes) of massive stars whose inner regions collapsed under their own gravity once their nuclear fuel was exhausted. The stars progressively sank to the cluster’s center after gravitational interactions with nearby less massive stars, leading to the small extent of the invisible mass concentration. Using the theory of stellar evolution, the scientists concluded that the bulk of the unseen concentration is made of stellar-mass black holes, rather than white dwarfs or neutron stars that are too faint to observe.

Scientists were expecting to find an intermediate-mass black hole at the heart of the globular cluster NGC 6397, but instead they found evidence of a concentration of smaller black holes lurking there. New data from the NASA/ESA Hubble Space Telescope have led to the first measurement of the extent of a collection of black holes in a core-collapsed globular cluster. Credit: ESA/Hubble, N. Bartmann

Two recent studies had also proposed that stellar remnants and in particular, stellar-mass black holes, could populate the inner regions of globular clusters.

“Our study is the first finding to provide both the mass and the extent of what appears to be a collection of mostly black holes in a core-collapsed globular cluster,” said Vitral.

Pictured here is the region around the globular cluster NGC 6397. Credit: ESA/Hubble, Digitized Sky Survey 2. Acknowledgement: Davide De Martin

“Our analysis would not have been possible without having both the Hubble data to constrain the inner regions of the cluster and the Gaia data to constrain the orbital shapes of the outer stars, which in turn indirectly constrain the velocities of foreground and background stars in the inner regions,” added Mamon, attesting to an exemplary international collaboration.

The astronomers also note that this discovery raises the question of whether mergers of these tightly packed black holes in core-collapsed globular clusters may be an important source of gravitational waves recently detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) experiment.

Reference: “Does NGC 6397 contain an intermediate-mass black hole or a more diffuse inner subcluster?” by Eduardo Vitral and Gary A. Mamon, 11 February 2021, Astronomy and Astrophysics.
DOI: 10.1051/0004-6361/202039650


Astronomical breakthrough sees background ‘hum’ of universe caused by gigantic black hole collisions finally detected

An international team of scientists say they have likely found traces of the gravitational waves that wash across the universe as gigantic black holes interact.

Our knowledge of gravitational waves suggests that the universe is full of them. The ripples occur every time black holes or neutron stars collide and every time a star collapses. The Big Bang would also have sent the waves cascading across the universe like ripples in a pond.

Over time, the gravitational waves become weak and hard to find, but experts believe they generate a background &lsquohum&rsquo that permeates throughout the universe.

Albert Einstein first theorized the waves way back in 1916, but they weren&rsquot actually detected until nearly a century later. That 2015 discovery scooped the 2017 Nobel Prize in Physics.

If it&rsquos confirmed, the freshly released research would herald yet another major milestone for astronomy, as it would allow scientists to examine extraordinary events, such as black holes colliding, that have not been possible to detect using the techniques of traditional light-based astronomy.

&ldquoIt is incredibly exciting to see such a strong signal emerge from the data,&rdquo said astrophysicist Joseph Simon of the University of Colorado Boulder, who is the lead researcher of the new paper.

However, because the gravitational-wave signal we are searching for spans the entire duration of our observations, we need to carefully understand our noise.

"This leaves us in a very interesting place, where we can strongly rule out some known noise sources, but we cannot yet say whether the signal is indeed from gravitational waves. For that, we will need more data,&rdquo Simon added.

The data in the new study was collected using the Green Bank antenna in West Virginia and the Arecibo Observatory in Puerto Rico before its recent collapse.


What is a black hole?

Though the center is temporarily closed, we are still passionate about sharing science and space exploration. In this series, we’ll take a quick tour through a science or space topic. Today we are exploring black holes.

Black holes have held our attention since their existence was first mathematically predicted by Albert Einstein’s General Theory of Relativity in 1915.

Long before our first sighting of these mysteries, they appeared in science fiction with perhaps one of the first film references in 1966 in Star Trek’s The Naked Time. In this early episode the Starship Enterprise encounters a Black Star and travels back in time three days. John Archibold Wheeler later coined the term “Black Hole” in 1967.

What is a black hole?

The most common way black holes form is from stellar death, when a large star, about 8-10 times the mass of our sun or 8-10 solar masses, reaches the end of its cycle. Inside a star, gravity pulls matter closer together while the nuclear fusion of hydrogen, the star’s fuel, radiates heat and pressure and pushes outward. Once the fuel supply is exhausted, the star implodes causing the outer shell to explode in a supernova.

What happens next depends on the size of the remaining core. If the remaining core of the star is less than 3 solar masses, gravity compresses the electrons and protons forming neutrons. The pressure of neutrons in contact with each other counteracts the force of gravity. The core, now stable and composed primarily of neutrons forms a neutron star.

If the core is greater than 3 solar masses, not even the neutron pressure can counteract the force of gravity and the remaining material will continue to contract and collapse on itself. All of the mass is condensed down into an incredibly small and dense point – the singularity.

The force of gravity is so strong that not even light can escape. The boundary of the black hole is the event horizon.


This artist’s impression depicts a rapidly spinning supermassive black hole surrounded by an accretion disc. This thin disc of rotating material consists of the leftovers of a Sun-like star which was ripped apart by the tidal forces of the black hole. Shocks in the colliding debris as well as heat generated in accretion led to a burst of light, resembling a supernova explosion. Credit: ESO, ESA/Hubble, M. Kornmesser/N. Bartmann

Can you see a black hole?

Although we cannot see the black hole, we can see the gas around it and observe the effects it has on mass and light. As predicted by Einstein, the immense mass and thus gravity of the black hole warps spacetime itself. Until recently, we could only observe this warping of light and gasses near a black hole, but not at its boundaries.

This changed Just a year ago, when the Event Horizon Telescope (ETH) array gave us our first image of the supermassive black hole located in galaxy M87, 53 million light years away. The ETH array is a collaboration of radio telescopes around the world synchronized to function as one virtual massive radio dish to provide a resolution power 4000 times greater than the Hubble Space Telescope. Data from the ETH estimates that the supermassive black hole is about 6.5 billion solar masses with a diameter of 24 billion miles (38 billion kilometers).

Studying black holes

Whether a black star, frozen star or black hole, these bodies still provoke questions, controversy and speculation and remain the fascination of both science and science fiction.

Are their event horizon boundaries “smooth” or “hairy” and surrounded by a ring of fire? Is information entering a black hole lost forever or can it still exist?

It is an exciting time for black hole research. Recent findings have begun to offer us answers via computer modeling and the production of acoustic or “dumb holes” which hope to finally corroborate Hawking radiation, proposed by Stephen Hawking in 1974.

The ETH has since added four additional telescopes, expanding to eight observatories and planning further observations for the spring of 2021. Together with other ground and space-based telescopes, scientists will continue to examine the questions of relativity and unravel the secrets of the universe.

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