SCIENTISTS have managed to prove that event horizons of a black hole are real and that matter disappears when it crosses such a point.

Black holes DO have event horizons which devour EVERYTHING around them

Once matter crosses the event horizon of a black hole it is unable to escape, according to boffins at the University of Texas at Austin.

Due to the intense gravitational pull of a black hole, not even light can become freed once it passes the point of no return.

The revelation goes one step further to proving Albert Einstein’s General Theory of Relativity.

Astrophysicist Pawan Kumar, from the university, said: "Our whole point here is to turn this idea of an event horizon into an experimental science, and find out if event horizons really do exist or not.

star impactMark A. Garlick/CfA
An artist's impression os a star impacting against a solid object

"Our motive is not so much to establish that there is a hard surface, but to push the boundary of knowledge and find concrete evidence that really, there is an event horizon around black holes.”

Scientists largely believe that at the heart of most galaxies lies a supermassive black hole, but one theory that is also recognised is that there might not be a black hole, but rather a ‘central massive object’ which has somehow managed to avoid collapsing in on itself to create a singularity – a point of infinite density – like how black holes are created.

black hole 2
"General relativity has passed another critical test."
To test this theory, Mr Kumar and his team discovered that if a star was to crash into this central object, it would create intense heat that could be detected, rather than being sucked into a black hole.
 
They then scanned through data from the Pan-STARRS telescope in Hawaii to look for instances in which this could have happened, but ultimately found none, essentially disproving the central massive object theory, and proving thew event horizon one.
 
Team member Ramesh Narayan from Harvard University said: "Our work implies that some, and perhaps all, black holes have event horizons and that material really does disappear from the observable Universe when pulled into these exotic objects, as we've expected for decades.
 
"General relativity has passed another critical test."
Source: This article was published express.co.uk By SEAN MARTIN
Categorized in Science & Tech

As the size of a black hole defined by the Schwarzschild radius relates to its mass, it's only by acquiring more mass that a supermassive black hole will grow larger, as a greater mass means spacetime is curved over a larger area. Note however that the Schwarzschild radius doesn't denote an actual surface, but the area beyond which spacetime is curved to such a degree that the escape velocity exceeds the speed of light. In other words, there is so much mass in such a small volume that the gravitational force curves spacetime to such extent that not even light can escape. As no light reflects, this is why a black hole is black.

Although it's thought that supermassive black holes can grow indefinitely, there is a theoretical maximum that it will be able to grow by means of the conventional accretion disc method, where gas in close proximity to the supermassive black hole becomes gravitationally attracted, passes the photon sphere and accretes into a disc as the material spirals into the black hole-beyond its event horizon (the boundary beyond which light cannot escape). This upper bound is 50 billion M☉ (solar mass).At that point-or usually way before that point has been reached-the gas in close proximity is exhausted, and the supermassive black hole stops acquiring more mass-except perhaps by tidally disrupting the occasional star that comes too close. Tidal disruption events are when a star comes too close to the black hole and is pulled apart by the black hole's tidal forces.

But supermassive black holes will be able to go beyond that upper bound by means of black hole mergers, which follow from galactic mergers; as galaxies merge, at one point the supermassive black holes at the center of both galaxies will enter a gravitational dance, spiral into each other and eventually merge to become one bigger supermassive black hole. Note also that as galaxies merge, some gas and stars will get close to the supermassive black hole again, meaning there is once again material in close proximity to the black hole, of which at least some material will spiral into the black hole and once again it can acquire more mass.

Above are two merging galaxies-the system NGC 2207 in the constellation Canis Major-which has ignited the supermassive black hole (the bright spot in the center of the main galaxy). Galactic mergers are the most likely reason why active galactic nuclei occur. Photo: ESO/Quora

As such, the current upper bound for the mass of supermassive black holes is merely a reflection of the current universe. After more time has passed and more galaxies have merged, that upper bound may increase somewhat. Supermassive black holes will never grow indefinitely however, as galactic mergers won't occur indefinitely, as dark energy (the force which accelerates the expansion of space) drives most galaxies apart.

Source: This article was published on dailymagazine.news by Martin Silvertant

Categorized in Science & Tech

NASA is in hot pursuit of a supermassive black hole that is hurtling through its galaxy.

NASA finds astonishing supermassive black hole HURTLING through galaxy

The huge phenomenon which has a mass of approximately 160 million times that of our sun and is being propelled at an astonishing speed.

Boffins at NASA believe that it could have been formed when two smaller black holes collided and merged. 

However, the experts believe that the gravitational waves generated by the clash could be stronger in one direction, causing the supermassive black hole, which are usually stationary and consume everything that crosses their path due to their immense gravitational pull, to be shot across the universe.

NASA said in a statement: “The strength of the kick depends on the rate and direction of spin of the two smaller black holes before they merge.

supermassive black hole
After all of this searching, a good candidate for a recoiling black hole was discovered.”

“Therefore, information about these important but elusive properties can be obtained by studying the speed of recoiling black holes.”

Scientists found the recoiling supermassive black hole candidate, which is in a galaxy 3.9 billion light years from Earth, by “sifting through X-ray and optical data for thousands of galaxies”.

 

 

black hole merge
NASA believes two black holes merged

They used observations from the Sloan Digital Sky Survey (SDSS) to look for X-ray emissions and correlated their findings with images from the Hubble Space Telescope to see if the supermassive blackhole is moving.

NASA said: “After all of this searching, a good candidate for a recoiling black hole was discovered.”

It added: “The host galaxy of the possible recoiling black hole also shows some evidence of disturbance in its outer regions, which is an indication that a merger between two galaxies occurred in the relatively recent past. 

“Since supermassive black hole mergers are thought to occur when their host galaxies merge, this information supports the idea of a recoiling black hole in the system.”

Source: This article was published express.co.uk By SEAN MARTIN

Categorized in Science & Tech

Astronomers have watched as a massive, dying star was likely reborn as a black hole. It took the combined power of the Large Binocular Telescope (LBT), and NASA's Hubble and Spitzer space telescopes to go looking for remnants of the vanquished star, only to find that it disappeared out of sight.

It went out with a whimper instead of a bang.

The star, which was 25 times as massive as our sun, should have exploded in a very bright supernova. Instead, it fizzled out—and then left behind a black hole.

A team of astronomers at The Ohio State University watched a star disappear and possibly become a black hole. Instead of becoming a black hole through the expected process of a supernova, the black hole candidate formed through a "failed supernova."
Credits: NASA’s Goddard Space Flight Center/Katrina Jackson

"Massive fails" like this one in a nearby galaxy could explain why astronomers rarely see supernovae from the most massive stars, said Christopher Kochanek, professor of astronomy at The Ohio State University and the Ohio Eminent Scholar in Observational Cosmology.

As many as 30 percent of such stars, it seems, may quietly collapse into black holes — no supernova required.

"The typical view is that a star can form a black hole only after it goes supernova," Kochanek explained. "If a star can fall short of a supernova and still make a black hole, that would help to explain why we don’t see supernovae from the most massive stars."

two images showing a star disappearing from a field
This pair of visible-light and near-infrared Hubble Space Telescope photos shows the giant star N6946-BH1 before and after it vanished out of sight by imploding to form a black hole. The left image shows the 25 solar mass star as it looked in 2007. In 2009, the star shot up in brightness to become over 1 million times more luminous than our sun for several months. But then it seemed to vanish, as seen in the right panel image from 2015. A small amount of infrared light has been detected from where the star used to be. This radiation probably comes from debris falling onto a black hole. The black hole is located 22 million light-years away in the spiral galaxy NGC 6946.
Credits: NASA, ESA, and C. Kochanek (OSU)

He leads a team of astronomers who published their latest results in the Monthly Notices of the Royal Astronomical Society.

Among the galaxies they've been watching is NGC 6946, a spiral galaxy 22 million light-years away that is nicknamed the "Fireworks Galaxy" because supernovae frequently happen there — indeed, SN 2017eaw, discovered on May 14th, is shining near maximum brightness now. Starting in 2009, one particular star, named N6946-BH1, began to brighten weakly. By 2015, it appeared to have winked out of existence.

After the LBT survey for failed supernovas turned up the star, astronomers aimed the Hubble and Spitzer space telescopes to see if it was still there but merely dimmed. They also used Spitzer to search for any infrared radiation emanating from the spot. That would have been a sign that the star was still present, but perhaps just hidden behind a dust cloud.

five images showing the sequence of a supernova
The doomed star, named N6946-BH1, was 25 times as massive as our sun. It began to brighten weakly in 2009. But, by 2015, it appeared to have winked out of existence. By a careful process of elimination, based on observations researchers eventually concluded that the star must have become a black hole. This may be the fate for extremely massive stars in the universe.
Credits: NASA, ESA, and P. Jeffries (STScI)

All the tests came up negative. The star was no longer there. By a careful process of elimination, the researchers eventually concluded that the star must have become a black hole.

It's too early in the project to know for sure how often stars experience massive fails, but Scott Adams, a former Ohio State student who recently earned his doctorate doing this work, was able to make a preliminary estimate.

"N6946-BH1 is the only likely failed supernova that we found in the first seven years of our survey. During this period, six normal supernovae have occurred within the galaxies we've been monitoring, suggesting that 10 to 30 percent of massive stars die as failed supernovae," he said.

"This is just the fraction that would explain the very problem that motivated us to start the survey, that is, that there are fewer observed supernovae than should be occurring if all massive stars die that way."

To study co-author Krzysztof Stanek, the really interesting part of the discovery is the implications it holds for the origins of very massive black holes — the kind that the LIGO experiment detected via gravitational waves. (LIGO is the Laser Interferometer Gravitational-Wave Observatory.)

It doesn't necessarily make sense, said Stanek, professor of astronomy at Ohio State, that a massive star could undergo a supernova — a process which entails blowing off much of its outer layers — and still have enough mass left over to form a massive black hole on the scale of those that LIGO detected.

"I suspect it's much easier to make a very massive black hole if there is no supernova," he concluded.

Adams is now an astrophysicist at Caltech. Other co-authors were Ohio State doctoral student Jill Gerke and University of Oklahoma astronomer Xinyu Dai. Their research was supported by the National Science Foundation.

NASA's Jet Propulsion Laboratory in Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington, D.C. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

The Large Binocular Telescope is an international collaboration among institutions in the United Sates, Italy and Germany.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

Source: This article was published nasa.gov

Categorized in Science & Tech

Huge numbers of supermassive black holes are visible in a stunning new photo that astronomers said is the deepest X-ray image of the sky ever captured.

The concentration of these light-gobbling monsters in the central region of the photo is unprecedented — the equivalent of 5,000 supermassive black holes over an area the size of the full moon, or 1 billion if extended across the entire night sky, researchers said.

"With this one amazing picture, we can explore the earliest days of black holes in the universe and see how they change over billions of years," Niel Brandt of Pennsylvania State University, who led a team of researchers studying the image, said in a statement.

The image incorporates about 80 days' worth of data collected by NASA's Chandra X-ray Observatory spacecraft and covers a patch of sky 8.5 light-years across. About seven out of every 10 objects in the photo are supermassive black holes, which lie at the hearts of galaxies and contain 100,000 to 10 billion times the mass of the sun, study team members said.

Chandra detects these black holes by spotting the X-ray radiation emitted by material spiraling toward the objects' event horizons, the points beyond which nothing, not even light, can escape.

"It can be very difficult to detect black holes in the early universe, because they are so far away and they only produce radiation if they're actively pulling in matter," study team member Bin Luo, of Nanjing University in China, said in the same statement. "But by staring long enough with Chandra, we can find and study large numbers of growing black holes, some of which appear not long after the Big Bang." 

Analyses of this treasure trove suggest that supermassive black holes grew in bursts, rather than gradually, in the first 1 billion to 2 billion years after the Big Bang, researchers said. In addition, the "seeds" of these behemoths are likely quite heavy, with masses between 10,000 and 100,000 times that of the sun, researchers said.

These findings could help explain a cosmic mystery: how supermassive black holes came to populate the early universe, despite not having much time to grow.

The team also determined that most of the X-ray emissions from massive, extremely distant galaxies — those 12 billion to 13 billion light-years away from Earth — likely came from stellar-mass black holes. These objects form after the death and collapse of stars much larger than the sun, and contain up to a few dozen solar masses.

Black Hole Quiz: How Well Do You Know Nature's Weirdest Creations?
Black holes are so bizarre, they sound unreal. Yet astronomers have found good evidence they exist. Test your knowledge of these wacky wonders. 
 
black hole particles escaping 

"By detecting X-rays from such distant galaxies, we're learning more about the formation and evolution of stellar-mass and supermassive black holes in the early universe," said study team member Fabio Vito, who's also based at Penn State. "We're looking back to times when black holes were in crucial phases of growth, similar to hungry infants and adolescents."

Author : Mike Wall

Source : http://www.space.com/35231-deepest-x-ray-image-black-holes.html

Categorized in Science & Tech

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