Black Holes

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Dormant black hole wakes up to devour passing star at theoretically impossible speed
'This is the first and only such event that has been caught at its peak'
Ian Johnston Science Correspondent

Video: [For some reason this plays intermittently on my system - a pity since it seems quite interesting.]

A dormant supermassive black hole woke up and devoured a star that had wandered too close, astronomers have discovered.
About 90 per cent of the black holes in the universe are not actively consuming matter on a significant scale, but if something like a star gets too close the results are spectacular.

An artist’s rendering of the encounter shows the star drifting through space, then being pulled apart by the black hole, creating a disk of material around it and sending out X-rays that were picked up by a Nasa satellite.
According to the research, the black hole consumed the star so quickly that it briefly exceeded the so-called Eddington Limit – the theoretical maximum “speed limit” that defines how fast a black hole can consume matter.

“Most tidal disruption events [stars being eaten by black holes] don’t emit much in the high-energy X-ray band,” said Dr Erin Kara, of Maryland University, who led the study.
“But there have been at least three known events that have, and this is the first and only such event that has been caught at its peak.
“Nasa’s Swift satellite saw it first and triggered the European Space Agency’s XMM-Newton satellite and the Japanese Aerospace Exploration Agency and NASA’s Suzaku satellite to target it for follow-up.
“So we have excellent data. We’re lucky that the one event we have is showing us all these exciting new things.”

Dr Kara said it was surprising that X-rays had originated from the disk of material so close to the black hole.
“Before this result, there was no clear evidence that we were seeing into the innermost regions of the accretion disk,” she said.
“This new study shows us that … we can see this reverberation at work very close to the central black hole.”

The discovery could help astronomers to understand how supermassive black holes grow to as much as several million times the mass of the sun.
“The meaning of this extends far beyond the studies of tidal disruption events,” said Dr Lixin Dai, a co-author on the study.
“It can help us understand how the biggest black holes in the universe formed and co-evolved with their host galaxies.”

http://www.independent.co.uk/news/s...-theoretically-impossible-speed-a7097001.html
 

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Black holes are ‘doors’ to another world, scientists say
You probably wouldn’t be able to survive the passage through the door, say the experts – likely ending up stretched out and ‘spaghettified’
Andrew Griffin

Black holes are doors to other parts of the universe, according to a new study. But you wouldn’t ever get to come back.

Anyone who managed to get through one of the mysterious doors would end up “spaghettified”, and stretched out like a long strand of pasta, according to the research. They’d get squished back down to size once they reached the other side, but it’s unlikely they’d be alive to see it.

Previously, scientists have held that all matter inside of a black hole is destroyed and so there would be no way of ever actually making it through. But the new research suggests that it could act as a doorway or a tunnel – as in a sci-fi story.

Black holes are places where matter has been squashed to such a density by gravity that the normal laws of physics break down.
The new theory rejects the view that at the centre of a black hole spacetime curves to an infinite point known as a "singularity" and all matter is destroyed.

Instead, it proposes that the heart of the simplest type of electrically charged, non-rotating black hole, is a very small spherical surface. This acts as a "wormhole" - a doorway or tunnel through the fabric of spacetime of the kind seen in countless sci-fi stories. In the movie Interstellar, a team of astronauts travel through a wormhole in search of a new home for humanity.

Dr Gonzalo Olmo, from the University of Valencia in Spain, said: "Our theory naturally resolves several problems in the interpretation of electrically-charged black holes.
"In the first instance, we resolve the problem of the singularity, since there is a door at the centre of the black hole, the wormhole, through which space and time can continue."
The wormhole predicted by the scientists' equations is smaller than an atomic nucleus, but gets bigger as more electrical charge is stored in the black hole.

A hypothetical traveller entering the black hole could be stretched thin enough to fit through the wormhole, like a strand of cotton threaded through the eye of a needle. :eek:

The new model also gets round the need for "exotic" energy or matter to create a wormhole.
According to Albert Einstein's theory of gravity, a wormhole can only appear in the presence of matter with highly unusual properties, possessing negative energy, pressure or density. Such "exotic matter" has never been observed.
"In our theory, the wormhole appears out of ordinary matter and energy, such as an electric field," said Dr Olmo.

The research is published in the journal Classical and Quantum Gravity.

http://www.independent.co.uk/news/s...to-another-world-scientists-say-a7174646.html

But I think non-rotating black holes are likely to be very unusual in the universe. Most things, Galaxies, stars and planets, do rotate.
 

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I caught part of a bbc radio prog a few days ago which took in black holes. A physicist [didn't get his name] was talking possibilities since nothing is known beyond the event horizon.

Started off with current theory: Massive star exhausts all it's fuel & goes supernova, remnant collapses under it's own gravity into super dense state & black hole forms.

He then theorises that once it's compacted down as dense as it can possibly get, it explodes & 'rebounds' but but because time runs much slower under dense gravitation, this could take millions or even billions of years viewed from a distance & in effect be unnoticeable from a human point of view. It could all happen in 'fairly short time' but would not be detectable due to gravitation. A sort of 'bouncing star' effect.

I filed it in the 'possibly plausible but beyond my real understanding' cabinet.
 

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Star Discovered in Closest Known Orbit Around Likely Black Hole

Astronomers have found evidence for a star that whips around a black hole about twice an hour. This may be the tightest orbital dance ever witnessed for a likely black hole and a companion star.

This discovery was made using NASA’s Chandra X-ray Observatory as well as NASA’s NuSTAR and CSIRO’s Australia Telescope Compact Array (ATCA). 



New Chandra data of this system, known as X9, show that it changes in X-ray brightness in the same manner every 28 minutes, which is likely the length of time it takes the companion star to make one complete orbit around the black hole. Chandra data also shows evidence for large amounts of oxygen in the system, a characteristic feature of white dwarfs. A strong case can, therefore, be made that the companion star is a white dwarf, which would then be orbiting the black hole at only about 2.5 times the separation between the Earth and the Moon.

“This white dwarf is so close to the black hole that material is being pulled away from the star and dumped onto a disk of matter around the black hole before falling in,” said first author Arash Bahramian of the University of Alberta in Edmonton, Canada, and Michigan State University in East Lansing. “Luckily for this star, we don’t think it will follow this path into oblivion, but instead will stay in orbit.”
More at link.
 

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Oh, great ... This new study suggests there are millions of black holes "kicked" into motion during their birth that are racing around within our own galaxy.
Millions of High-Speed Black Holes Could Be Zooming Around The Milky Way

How are black holes born? Astrophysicists have theories, but we don't actually know for certain. It could be massive stars quietly imploding with a floompf, or perhaps black holes are born in the explosions of colossal supernovas. New observations now indicate it might indeed be the latter.

In fact, the research suggests that those explosions are so powerful, they can kick the black holes across the galaxy at speeds greater than 70 kilometres per second (43 miles per second).

"This work basically talks about the first observational evidence that you can actually see black holes moving with high velocities in the galaxy and associate it to the kick the black hole system received at birth," astronomer Pikky Atri of Curtin University and the International Centre for Radio Astronomy Research (ICRAR) told ScienceAlert.

And it means there are potentially millions stellar-mass black holes zooming around the galaxy at high speed. The paper, currently available in pre-print, has been accepted into the Monthly Notices of the Royal Astronomical Society. ...
FULL STORY: https://www.sciencealert.com/there-...h-speed-black-holes-zooming-around-the-galaxy
 

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Team plans colour film of black hole at galaxy's centre

The team that took the first ever image of a black hole last year has announced plans to capture "razor sharp" full colour video of the one at the centre of our galaxy.

The scheme proposes 3 small satellites to add to the ground based telescopes making a combined telescope effectively larger than the Earth.

The international consortium expects to add ground-based telescopes in Greenland, France and parts of Africa and has applied for funding from the US National Science Foundation (NSF) to send three small satellites into orbit to supplement the ground-based survey.

According to Prof Falcke, this will create a super telescope, effectively larger than the Earth, capable of taking razor sharp images of the black hole at the centre of our galaxy.

Prof Shep Doleman of Harvard University, US, who is the EHT's project director, said the images and video would enable the team to test Einstein's theories to new limits and unravel how black holes generate light-speed jets that can pierce entire galaxies.

"(We plan to) create huge virtual telescopes, and new radio facilities will be built around the globe. The EHT team is just getting started," he said.
 

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Black hole at centre of galaxy is getting hungrier, say scientists

Scientists say Milky Way’s Sagittarius A* has been more active in recent months

Unseeable and inescapable, black holes already rank among the more sinister phenomena out in the cosmos. So it may come as disconcerting news that the supermassive black hole at the centre of the Milky Way appears to be growing hungrier.

Astronomers monitoring the colossal object, called Sagittarius A*, found that in the past year it appears to have consumed nearby matter at an unprecedented rate.
(c) The Guardian. '19
 

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Possible new type of small black hole discovered

A team of astronomers from Ohio State University claim to have discovered an object that belongs to a previously missing class of black holes.

Thompson and his team were puzzled by the huge gap between the size of the biggest neutron stars - extremely dense and relatively small stars that form after larger stars implode after a supernova - and the smallest black holes we know of.

Their smoking gun: a giant red star that was orbiting something that at first appeared to be too small to be a black hole in the Milky Way, but was much bigger than the neutron stars we know of.

Their finding really did turn out to be a low-mass black hole, and it was only 3.3 times the mass of the Sun - usually the black holes we've found in the past are at least five times the Sun's mass or much, much larger.

The discovery could redefine the way we look at the life cycle of a star.

"If we could reveal a new population of black holes, it would tell us more about which stars explode, which don't, which form black holes, which form neutron stars," said Thompson. "It opens up a new area of study."
 

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Black Holes Grow Hair, Then Go Bald Again

Source: Live Science
Date: 20 November, 2019

Thanks to their tendency to suck in everything around them — even light — black holes don't divulge clues about their origins or histories. This frustrating fact led scientists in the 1960s to declare that black holes "have no hair." By this, researchers meant that black holes had very few distinguishing characteristics to separate one from another.

Now, new calculations suggest that some black holes can grow hair...

https://www.livescience.com/black-holes-can-grow-hair-temporarily.html
 

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Hologram Within a Hologram Hints at Fate of Black Holes

Source: Quanta Magazine
Date: 19 November, 2019

ike cosmic hard drives, black holes pack troves of data into compact spaces. But ever since Stephen Hawking calculated in 1974 that these dense spheres of extreme gravity give off heat and fade away, the fate of their stored information has haunted physicists.

The problem is this: The laws of quantum mechanics insist that information about the past is never lost, including the record of whatever fell into a black hole. But Hawking’s calculation contradicted this.

https://www.quantamagazine.org/holo...n-to-black-hole-information-paradox-20191119/
 

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Astronomers discover supermassive black hole in the Milky Way galaxy 70 TIMES larger than the Sun that according to current scientific understanding should NOT exist

Source: Daily Mail online
Date: 28 November, 2019

Astronomers have discovered a black hole in the Milky Way so massive that it challenges existing models of how stars evolve.

Called LB-1, this black hole is 15,000 light years from Earth and has a mass 70 times greater than the Sun.

LB-1's large mass falls into a range known as the 'pair instability gap' where supernovae should not have produced it, leading experts to believe this is a new kind a black hole, formed by another physical mechanism.

https://www-dailymail-co-uk.cdn.ampproject.org/v/s/www.dailymail.co.uk/sciencetech/article-7732399/amp/Scientists-spot-black-hole-huge-shouldnt-exist-galaxy.html?amp_js_v=a2&amp_gsa=1&usqp=mq331AQCKAE=#referrer=https://www.google.com&amp_tf=From %1$s&ampshare=https://www.dailymail.co.uk/sciencetech/article-7732399/amp/Scientists-spot-black-hole-huge-shouldnt-exist-galaxy.html#referrer=https%3A%2F%2Fwww.google.com&amp_tf=From%20%251%24s

See also:

https://www.independent.co.uk/life-...ar-size-record-galaxy-milky-way-a9220696.html
 

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This Stunning Video on The True Scale of Black Holes Might Just Crush Your Brain

Source: sciencealert.com
Date: 28 November, 2019

Black Holes are vast, matter-annihilating objects that seem to defy physics by their very existence. They're so weird, that when Albert Einstein's equations first predicted the existence of these beasts, he didn't believe they could actually be real.

And you can't really blame him, because the idea that we have these matter-sucking singularities of space-time scattered all around our cosmic backyard is pretty hard to wrap your head around.

But as people who write about black holes a lot, we figured we were past being shocked by how strange and massive they are.

That is, until we saw this video from YouTube channel morn1415, famous for their size comparisons of various objects in the Universe.

https://www-sciencealert-com.cdn.am...le-of-black-holes-might-just-crush-your-brain
 

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The Pure Chaos of Magnetic Fields May Explain The Intense Shine of Black Holes

Source: sciencealert.com
Date: 4 December, 2019

There's some irony in the fact that the darkest objects in the sky - black holes - can be responsible for some of the Universe's brightest light. Simulations of the magnetic fields surrounding black holes and neutron stars have now provided new insights into their astonishing brilliance.

https://www-sciencealert-com.cdn.am...esponsible-for-the-black-hole-s-intense-shine
 

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Black holes formed from dark matter could be making dead stars explode

Source: newscientist.com
Date: 6 December, 2019

Dead stars are exploding all around the universe and we aren’t really sure why – but now a pair of researchers think that minuscule black holes made from dark matter might be to blame.

Burnt out stars known as white dwarfs can ignite into a type Ia supernova when they gather matter from a neighbouring star or merge with other astronomical objects. Exactly how this works is still an open question.

https://www-newscientist-com.cdn.am...3A%2F%2Fwww.google.com&amp_tf=From%20%251%24s
 

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You Cannot Conceive of the Hugeness of This Black Hole

Source: gizmodo.co.uk
Date: 06 December, 2019

Oh my, this recently discovered black hole... well, it’s big.

How big? Among black holes whose masses scientists can directly infer based on the motion of their host galaxies’ stars, it’s the biggest. It’s 40 billion times the mass of the Sun big—that’s around 2.5 percent the mass of the entire Milky Way galaxy.

[...]

But is it the biggest black hole possible?

“We actually don’t know how big black holes can be,” Jens Thomas, one of the study’s authors from the Max Planck Institute for Extraterrestrial Physics, told Gizmodo.

https://www.gizmodo.co.uk/2019/12/you-cannot-conceive-of-the-hugeness-of-this-black-hole/
 

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How did supermassive black holes grow so fast?

Source: phys.org
Date: 7 hours ago

Black holes in the early universe pose a bit of a problem. Based on observations from telescopes on Earth and in space, we know that some black holes grew to be a billion times the mass of the sun just one billion years after the Big Bang. Our current models of black hole growth, however, can't explain this speed of growth. So how did these supermassive black holes come about?

This is a problem that has long plagued astronomers. Our current understanding suggests that in this time frame, only so-called intermediate mass black holes up to 100,000 times the mass of our Sun should have been able to grow. And while several theories for this rapid early black hole growth have been proposed, the answer remains elusive.

"That is still a huge problem in astrophysics," said Dr. John Regan, an astrophysicist from Dublin City University, Ireland.

https://phys-org.cdn.ampproject.org...ws/2019-12-supermassive-black-holes-fast.html
 

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Astronomers discover supermassive black hole in the Milky Way galaxy 70 TIMES larger than the Sun that according to current scientific understanding should NOT exist

Astronomers have discovered a black hole in the Milky Way so massive that it challenges existing models of how stars evolve.
Called LB-1, this black hole is 15,000 light years from Earth and has a mass 70 times greater than the Sun. ...
Oops ... Maybe not ... :sorry:
Impossibly Big Black Hole Was Probably Impossible After All

A straightforward error in analysis undermines the entire paper.

Two weeks ago (Nov. 27), astronomers published a paper in the journal Nature claiming they'd found an impossibly gigantic black hole not too far from Earth. If they were correct, it would have been a major shock to astrophysics, upending theories of how and where such huge black holes form. But it looks like they were probably wrong.

The researchers thought they'd found the rare, huge black hole, 70 times the mass of our sun, as part of a binary system known as LB-1 that is 15,000 light-years from Earth. But now, two independent papers published to the arXiv database this week found the same basic problem with that claim: It relied on evidence that the unseen black hole was wiggling very slightly as its heavy companion star, known as the B star, wheeled around it. The difference between the black hole's slight wiggle and the star's rapid motion suggested the black hole was much larger — if they were closer to one another's size, you'd expect the black hole to move as much as the star. However, according to the two new papers, the researchers misinterpreted what they were seeing in the light from the distant system. ...
FULL STORY: https://www.livescience.com/impossibly-huge-black-hole-debunked.html
 

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Our Galaxy Might Have — Two! — Black Holes at Its Center

Source: futurism.com
Date: 13 December, 2019

We already know our galaxy, the Milky Way, as home to Sagittarius A*, a black hole with a mass about 4 million times that of the Sun.

But an international team of astrophysicists suspects that Sgr A* might have a smaller companion black hole. Now, they think they’ve figured out how to determine if they’re right.

On Thursday, UCLA astrophysicist Smadar Naoz’s had a story published in Conversation detailing paper she and her colleagues shared on the pre-print server arXiv. Based on their observations of star S0-2, which orbits Sgr A* every 16 years, the researchers know that the Milky Way’s supermassive black hole couldn’t have a companion with a mass greater than 100,000 times that of our Sun. But they aren’t ruling out a smaller “hidden friend.”

https://futurism-com.cdn.ampproject...futurism.com/milky-way-galaxy-two-black-holes
 

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ESO observations reveal black holes' breakfast at the cosmic dawn

Source: phys.org
Date: 19 December, 2019

Astronomers using ESO's Very Large Telescope have observed reservoirs of cool gas around some of the earliest galaxies in the Universe. These gas halos are the perfect food for supermassive black holes at the centre of these galaxies, which are now seen as they were over 12.5 billion years ago. This food storage might explain how these cosmic monsters grew so fast during a period in the Universe's history known as the Cosmic Dawn.

"We are now able to demonstrate, for the first time, that primordial galaxies do have enough food in their environments to sustain both the growth of supermassive black holes and vigorous star formation," says Emanuele Paolo Farina, of the Max Planck Institute for Astronomy in Heidelberg, Germany, who led the research published today in The Astrophysical Journal. "This adds a fundamental piece to the puzzle that astronomers are building to picture how cosmic structures formed more than 12 billion years ago."

https://phys-org.cdn.ampproject.org...2019-12-eso-reveal-black-holes-breakfast.html
 

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A Strange Black Hole Is Shooting Out Wobbly Jets Because It's Dragging Spacetime

Source: sciencealert.com
Date: 1 January, 2020

Some 7,800 light-years away, in the constellation of Cygnus, lies a most peculiar black hole. It's called V404 Cygni, and in 2015, telescopes around the world stared in wonder as it woke from dormancy to devour material from a star over the course of a week.

That one event provided such a wealth of information that astronomers are still analysing it. And they have just discovered an amazing occurrence: relativistic jets wobbling so fast their change in direction can be seen in mere minutes.

And, as they do so, they puff out high-speed clouds of plasma.

"This is one of the most extraordinary black hole systems I've ever come across," said astrophysicist James Miller-Jones of the International Centre for Radio Astronomy Research (ICRAR) at Curtin University in Australia back in April.

https://www-sciencealert-com.cdn.am...t-wobbly-jets-because-it-s-dragging-spacetime
 

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Black holes shouldn't echo, but this one might. Score 1 for Stephen Hawking?

Source: livescience.com
Date: 27 January, 2020

When two neutron stars slammed together far off in space, they created a powerful shaking in the universe — gravitational waves that scientists detected on Earth in 2017. Now, sifting through those gravitational wave recordings, a pair of physicists think they've found evidence of a black hole that would violate the neat model drawn from Albert Einstein's theory of general relativity.

In general relativity, black holes are simple objects: infinitely compressed singularities, or points of matter, surrounded by smooth event horizons through which no light, energy or matter can escape. Until now, every bit of data we've gleaned from black holes has supported this model.

But in the 1970s, Stephen Hawking wrote a series of papers suggesting that the borders of black holes aren't quite so smooth. Instead, they blur thanks to a series of effects linked to quantum mechanics that allow "Hawking radiation" to escape. In the years since, a number of alternative black hole models have emerged, where those smooth, perfect event horizons would be replaced with flimsier, fuzzier membranes. More recently, physicists have predicted that this fuzz would be particularly intense around newly formed black holes — substantial enough to reflect gravitational waves, producing an echo in the signal of a black hole's formation. Now, in the aftermath of the neutron star collision, two physicists think they've found that type of echo. They argue that a black hole that formed when the neutron stars merged is ringing like an echoing bell and shattering simple black hole physics.

If the echo is real, then it must be from the fuzz of a quantum black hole, said study co-author Niayesh Afshordi, a physicist at the University of Waterloo in Canada.

https://www-livescience-com.cdn.amp...hole-echoes-unsettle-einstein-relativity.html
 

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Calculating Hawking radiation at the event horizon of a black hole

Source: RUDN University / phys.org
Date: 31 January, 2020

A RUDN University physicist has developed a formula for calculating Hawking radiation on the event horizon of a black hole, which allows physicists to determine how this radiation would be changed with quantum corrections to Einstein's theory of gravity. This formula will allow researchers to test the accuracy of different versions of the quantum gravity theory by observing black holes, and comprises a step toward the long-sought "grand unification theory" that would connect quantum mechanics and relativity. The article is published in the journal Physical Review D.

Although Einstein's gravitation theory corresponds to the recent discovery of gravitation waves, it still leaves open some questions, including the nature of the singularity, dark matter, dark energy, and the question of quantum gravity. Also, even observations of gravity waves do not exclude that alternative gravitation theories may be accurate, and they can be used to describe black holes. Such theories, which include additional quantum components, do not contradict the observed picture of black hole mergers. Calculations made following these theories predict the same behavior of black holes at a great distance from each other, but at the same time, demonstrate important features near the event horizon—the "border" of the black hole from beyond which there is no return.

It is believed impossible to look beyond the event horizon of a black hole because nothing can escape, including particles and radiation. However, Stephen Hawking proved that black holes can "evaporate" by emitting various elementary particles. This means that over time, all the information absorbed by a black hole can disappear, which is contrary to fundamental ideas about information—it is believed that information cannot disappear without a trace. Therefore, alternative gravitation theories, aimed at eliminating this paradox, have become more popular since they could contribute to a quantum gravitation theory.

https://phys-org.cdn.ampproject.org...2020-01-hawking-event-horizon-black-hole.html
 

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Quantum mechanics means some black hole orbits are impossible to predict

Foreseeing the paths of three orbiting objects sometimes requires precision better than the quantum limit.

Source: www.sciencenews.org
Date: 6 April, 2020

Even if you could measure three black holes’ locations as precisely as physically possible, you still might not know where the black holes would go. Such a trio’s complex dance can be so chaotic that the motions are fundamentally unpredictable, new computer simulations show.

The paths of three black holes orbiting each other can be calculated based on their positions and velocities at one point in time. But in some cases, the orbits depend so sensitively on the black holes’ exact positions that the uncertainty of quantum physics comes into play. Tiny quantum uncertainties in specifying the locations of objects can explode as the black holes’ gyrations continue over tens of millions of years, astrophysicist Tjarda Boekholt and colleagues report in the April Monthly Notices of the Royal Astronomical Society. So the distant future of the black holes’ orbits is impossible to foresee.

Such extreme sensitivity to initial conditions is known as chaos. The new study suggests, in the case of three black holes, “quantum mechanics imprints into the universe chaos at a fundamental level,” says astrophysicist Nathan Leigh of Universidad de Concepción in Chile, who was not involved with the research.

[...]

http://www.sciencenews.org/article/quantum-mechanics-some-black-hole-orbits-impossible-predict/amp
 

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Astronomers Predict Astonishing Flare From Two Swirling Supermassive Black Holes

Source: sciencealert.com
Date: 30 April, 2020

In the depths of space 3.5 billion light-years away, two supermassive black holes are locked in one of the most extreme orbital dances in the Universe. Their riotous, somewhat erratically flaring death spiral has been documented for decades.

With new observations, astronomers have now characterised the way they whirl about each other in the centre of a galaxy called OJ 287. In turn, that characterisation has helped to refine our understanding of whether or not black holes are 'hairy', a conundrum that has puzzled cosmologists for decades.

OJ 287 is no ordinary galaxy. It's a blazar, with a highly variable active galactic nucleus and a relativistic jet beaming at Earth. For over a century, it's been documented spitting out dazzling flares of radiation at semi-regular intervals.

At its core, OJ 287 is even more intense than most galactic nuclei. It has not one, but two supermassive black holes, and they are chonkers.

The smaller of the two would power a very respectable galactic nucleus in its own right, coming in at 150 million times the mass of the Sun. Our own Milky Way's supermassive black hole is 4 million solar masses.

The larger of the two is one of the most massive black holes we've ever seen. It tips the cosmic scales at 18 billion solar masses.

[...]

https://www.sciencealert.com/the-dance-of-two-supermassive-black-holes-kicks-up-repeated-flares
 

EnolaGaia

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Ruh-roh ... Black holes are closer, and less conspicuous, than we previously thought ...
Astronomers discover closest black hole to Earth. And you can 'see' it.

A newfound black hole may be the closest black hole to Earth, and you can spot its cosmic home in the night sky without a telescope.

The black hole, which is lurking 1,000 light-years from Earth in the southern constellation of Telescopium, belongs to a system with two companion stars that are bright enough to observe with the naked eye. But you won't be able to see the black hole itself; the massive object has such a strong gravitational pull that nothing — not even light — can escape it.

Astronomers discovered this black hole while studying what they thought was just a binary star system, or two stars that orbit a common center of mass. They were using the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile to observe the binary, known as HR 6819, as part of a broader study on double star systems. When they analyzed their observations, the researchers were shocked to learn that a third object was hiding in the system: a black hole. ...

Although the astronomers could not directly observe the black hole, they were able to infer its presence based on its gravitational interactions with the other two objects in the system. ...

After HR 6819's black hole, the nearest known black hole is about 3,000 light-years away from Earth in the constellation Monoceros. But there could still be others lurking even closer that have yet to be detected; astronomers estimate that there are millions of black holes in our galaxy alone.

The black hole in HR 6819 is one of the first stellar-mass black holes found in our galaxy that does not release bright X-rays while violently interacting with its companion stars, and the discovery could help researchers find other similarly "quiet" black holes in the Milky Way, according to the statement. ...
FULL STORY: https://www.livescience.com/closest-black-hole-to-earth-discovered.html

See Also:
https://www.sciencealert.com/astron...-black-hole-just-1-000-light-years-from-earth
 
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Comfortably Numb

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Black holes? They are like a hologram

Source: phys.org
Date: 4 June, 2020

According to new research by SISSA, ICTP and INFN, black holes could be like holograms, in which all the information to produce a three-dimensional image is encoded in a two-dimensional surface.

As affirmed by quantum theories, black holes could be incredibly complex, and concentrate an enormous amount of information in two dimensions, like the largest hard disks that exist in nature.

This idea aligns with Einstein's theory of relativity, which describes black holes as three dimensional, simple, spherical and smooth, as depicted in the first-ever image of a black hole that circulated in 2019. In short, black holes appear to be three dimensional, just like holograms. The study, which unites two discordant theories, has recently been published in Physical Review X.

[...]

To study black holes, the two authors of the new study, Francesco Benini (SISSA Professor, ICTP scientific consultant and INFN researcher) and Paolo Milan (SISSA and INFN researcher), used a 30-year-old idea called the holographic principle.

The researchers write, "This revolutionary and somewhat counterintuitive principle proposes that the behavior of gravity in a given region of space can alternatively be described in terms of a different system, which lives only along the edge of that region and therefore in a one less dimension. And, more importantly, in this alternative description (called holographic), gravity does not appear explicitly.

In other words, the holographic principle allows us to describe gravity using a language that does not contain gravity, thus avoiding friction with quantum mechanics."

[...]

https://phys.org/news/2020-06-black-holes-hologram.html
 

EnolaGaia

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New research results indicate the hypothetical "Penrose process" for extracting energy from a black hole is indeed theoretically possible.
After 50 Years, Experiment Finally Shows Energy Could Be Extracted From a Black Hole

A 50-year-old theoretical process for extracting energy from a rotating black hole finally has experimental verification.

Using an analogue of the components required, physicists have shown that the Penrose process is indeed a plausible mechanism to slurp out some of that rotational energy - if we could ever develop the means.

That's not likely, but the work does show that peculiar theoretical ideas can be brilliantly used to explore the physical properties of some of the most extreme objects in the Universe. ...

This singularity sits inside a region called the event horizon - the point at which the gravity around the black hole is so strong, not even light-speed is sufficient to achieve escape velocity. And outside the event horizon, an extended region of space-time becomes twisted as it's dragged along with the black hole's rotation, an effect called frame-dragging.

This is where the Penrose process comes in. In 1969, mathematical physicist Roger Penrose proposed that a region just outside the event horizon called the ergosphere, where frame-dragging is at its strongest, could be exploited to extract energy.

According to Penrose's calculations, if an object dropped into the ergosphere were to split in two, one part would be flung beyond the event horizon.

The other, however, would be accelerated outwards, with an additional kick from the black hole. If everything went just right, it would emerge from the ergosphere with around 21 percent more energy than it entered with. ...
FULL STORY: https://www.sciencealert.com/an-exp...w-energy-could-be-extracted-from-a-black-hole
 

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EnolaGaia

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A massive blue variable star approaching "stellar death" simply "wasn't there" when astronomers went looking for it in 2019.

One proposed explanation is that the star collapsed to become a black hole as expected, but without exploding as a supernova. It this was indeed the case, it would be the first known example of such a quiet stellar demise.
Massive 'disappearing' star could have become a black hole without going supernova

The star's mysterious disappearance could hint at a new type of stellar death.

In 2019, scientists witnessed a massive star 2.5 million times brighter than the sun disappear without a trace.

Now, in a new paper published today (June 30) in the journal Monthly Notices of the Royal Astronomical Society, a team of space detectives (see: astrophysicists) attempt to solve the case of the disappearing star by providing several possible explanations. Of these, one twist ending stands out: Perhaps, the researchers wrote, the massive star died and collapsed into a black hole without undergoing a supernova explosion first — a truly "unprecedented" act of stellar suicide. ...

One explanation could be that the star dimmed considerably after its outburst, and was then further obscured by a thick veil of cosmic dust. If this were the case, then the star could reappear in future observations.

The weirder and more exciting explanation is that the star never recovered from its outburst, but instead collapsed into a black hole without going supernova. This would be a rare event, the team conceded. Given the star's estimated mass before its disappearance, it could have created a black hole measuring 85 to 120 times the mass of Earth's sun, though how this could have happened without a visible supernova is still an open question. ...
FULL STORY: https://www.livescience.com/disappearing-star-black-hole-no-supernova.html
 
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