Astronomy

Why do “they” portray colliding black holes like that?

Why do “they” portray colliding black holes like that?


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When I see an animation of two colliding black holes anywhere, it looks like two merging beads of water. But why would the event horizon form a bridge during collision? There is no material flowing in-between. Wouldn't the event horizons "push" each-other away as they merge?(the effect not the black hole itself) For what I understand the gravity would poorly, but surely, be canceled out. Wouldn't this "push" only disappear from view as they got significantly closer, where it still exists but is trapped in a much larger one?

Just to make sure, as I see the similar questions: I don't mean what happens as they collide, but rather why isn't this portrayed if it does this effect at all?


The event horizon is not a physical structure. Rather it is the boundary of a region of spacetime from which no information can escape. If you were (unfortunate enough to be) between two black holes, you may be in a position in which there is no net force, and yet you could not travel from your location to the point distant from the two black holes, no matter how fast you were able to move.

If you were in such a position, you would be inside the event horizon of the two black holes.

Finding the event horizon means solving the Field equations of General relativity. Exact solutions are known in several situations: A single mass concentrated at a point, a mass with a charge and a rotating mass. If there are two masses, then the Field equations have no exact solution, but can be solved numerically (with a fast enough supercomputer) It is the results of these calculations that you are seeing.

So, the shape you see is the event horizon, The event horizon of two nearby black holes can be calculated by a computer. Since you may be trapped between two black holes the event horizon will be deformed towards another black hole's event horizon, giving the "teardrop-> bridge->merger" appearance of the final moments of two back holes.


Why do &ldquothey&rdquo portray colliding black holes like that? - Astronomy

That is a very interesting question and it happens to be on the fore-front of modern Astrophysics and General Relativity.

If two bodies (stars, black holes, anything) get close enough to be gravitationally bound they will develop some sort of orbit in which the two bodies circle each other.

Einstein's theory of General Relativity predicts that when two very massive objects(like Black Holes and Neutron Stars) are caught in an orbit like this they will generate Gravitational Waves (Ripples in Space-Time). These Gravitational Waves carry energy away from the orbiting bodies which means that with each successive revolution they get closer to each other. Eventually the orbit gets so small that the two bodies merge.

The merger of two black holes entails a lot of complicated General Relativity and some non-intuitive physics, but theorists use large supercomputers to simulate such events. There are two primary results to these mergers of which we can be sure of:

There are currently several projects which are attempting to directly detect the disturbances in space time caused by gravitational waves. One is called LIGO, and they primarily expect to "see" the results of neutron star and black hole binary mergers. Another is called NANOGrav and the IPTA, and they expect to "see" the final stages and final mergers of pairs of supermassive black holes in the centers of colliding galaxies.

There is also quite a bit of evidence that black holes merge in distant galaxies from electromagnetic observations (light), from observations of jet streams caused by the moving black holes, to periodicities in the observed brightness of some of these systems, to simulations of galaxy formation and merger histories.

This page was last updated October 2, 2015.

About the Author

Marko Krco

Marko has worked in many fields of astronomy and physics including planetary astronomy, high energy astrophysics, quantum information theory, and supernova collapse simulations. Currently he studies the dark nebulae which form stars.


Why do you like astronomy?

After a long absence, my youg son actually reignited my interest in the heavens. I too had the cheap-o plastic refractor as a kid. you've all heard the story before.

When he asked for a scope a couple years ago, I started doing the research. I had no idea how far the technology had come, and how affordable a good scope can be. I purchased an ETX 125 for him, and we both fell in love with it. Then came the LX200, etc.

So why do I like astronomy? Foremost, it affords me valuable, quality time with my son. Second, I just love the mystery of the cosmos, the excitement of seeing something new, and the relaxation.

#27 molniyabeer

I studied geology in college and loved reading McPhee for the clear, engaging way he wrote about the field. In one of his books, he discusses the concept of deep time, the almost unknowable span of years recorded in the rock record. He quotes a geologist with something like "If you free your mind to the conventional reaction to a quantity like a million years, you begin to live on a timescale that is the earth's timescale. And then in a way you never live at all. But in another, you live forever."

For me, astronomy, with the vastness of space that my scope only begins to pick at, is another way of living forever.

#28 jfosc

I'm a big science buff, especially astronomy and cosmology. I always loved learning about the cosmos growing up and I'm always in awe of the beautiful pictures that come back from hubble, probes, etc.

Now that I have a dob, I'm enjoying learning the sky manually. It's frustrating sometimes, but anything worth doing isn't easy.

When I find something new I feel the work has paid off. Sure, we all know the views are not as spectacular as Hubble images, but I feel being able to at these objects with my own eyes is a gift.

#29 katodog

Because no matter what, it's only me and the sky. I could have the worst day of my life, and if I can get out with the scopes, even for only a few minutes, it's the best day of my life.

Where else can you go and be completely and totally alone but in the middle of space. Especially out by my inlaws, where the only thing you hear is the crickets, and there's nothing but a billion stars and you. It's the only place you can go and be totally lost in a world without crime, and death, and crying babies, and honking horns, and bad people. It's the only place where no one expects anything of you, and you expect nothing of it, except the thrill of a stunning view. It's the only place where who you are and what you do doesn't matter. You don't need to worry about what the stars think of you, and they ask nothing of you except to be their companion for a while.

For me, it's the best end to another day on this planet. It's the best way for my anger and my stress to flow away. I used to use my Martial Arts, and meditation, to take me away from things, but astronomy has always been the one true thing to keep me sane.

You can't tell me that there isn't a single person who, if even for the first and only time, wasn't completely floored by their first real view through a telescope. There's still many times when I look through the eyepiece and can't believe it's me standing there seeing that.

It all sounds mushy and weird, and I make jokes about the money I spend and the things I do. But when it all comes down to the bare nuts and bolts, Astronomy is the only thing that you could do bad, and still have a genuinely great time.

Even if it's cloudy out, you can still enjoy it. You can wash and wax (hi Mark) your equipment. You can tinker with modifications, or rearrange your eyepiece case again.

You can even come here, to Cloudy Nights, and enjoy something wonderful with someone you've never met, but feel like you've known forever. You can finally find someone who enjoys astronomy the way you do, with your complete mind, heart, and soul.

And if that doesn't work, then how about this. Astronomy is the only hobby where you can sit out in public for hours on end with some of the most sinister looking equipment around, and not get into a heap of trouble.

#30 mazzefr

I'll take door number three.

Because no matter what, it's only me and the sky. I could have the worst day of my life, and if I can get out with the scopes, even for only a few minutes, it's the best day of my life.

Where else can you go and be completely and totally alone but in the middle of space. Especially out by my inlaws, where the only thing you hear is the crickets, and there's nothing but a billion stars and you. It's the only place you can go and be totally lost in a world without crime, and death, and crying babies, and honking horns, and bad people. It's the only place where no one expects anything of you, and you expect nothing of it, except the thrill of a stunning view. It's the only place where who you are and what you do doesn't matter. You don't need to worry about what the stars think of you, and they ask nothing of you except to be their companion for a while.

For me, it's the best end to another day on this planet. It's the best way for my anger and my stress to flow away. I used to use my Martial Arts, and meditation, to take me away from things, but astronomy has always been the one true thing to keep me sane.

You can't tell me that there isn't a single person who, if even for the first and only time, wasn't completely floored by their first real view through a telescope. There's still many times when I look through the eyepiece and can't believe it's me standing there seeing that.

It all sounds mushy and weird, and I make jokes about the money I spend and the things I do. But when it all comes down to the bare nuts and bolts, Astronomy is the only thing that you could do bad, and still have a genuinely great time.

Even if it's cloudy out, you can still enjoy it. You can wash and wax (hi Mark) your equipment. You can tinker with modifications, or rearrange your eyepiece case again.

You can even come here, to Cloudy Nights, and enjoy something wonderful with someone you've never met, but feel like you've known forever. You can finally find someone who enjoys astronomy the way you do, with your complete mind, heart, and soul.

And if that doesn't work, then how about this. Astronomy is the only hobby where you can sit out in public for hours on end with some of the most sinister looking equipment around, and not get into a heap of trouble.

#31 Tim61

#32 Bubbinski

I like it because it gives me a chance to look at fascinating and spectacular stuff. I've always been curious about space since I was little, ever since my grandpa took me to Flandrau Planetarium as a little boy living in Tucson. That was a life changing experience for me, I think.

I just enjoy looking at the planets, the Moon, and now double stars and DSO's, as well as satellites flying overhead. You always experience the sky a little differently each night, and it's a great way to decompress.

Tonight was a clear night, but I didn't use my scope. instead I felt like using my binoculars. For one thing, ISS/shuttle was passing overhead. It was pretty spectacular, and rivaling Venus in brightness. Not two minutes after ISS passed over, I saw another satellite going from north to south in what appeared to be a polar orbit. I then swept my binos through "Messier Country", making it a point to take in M7, and also looking at Cygnus, Lyra, M13, the area around Arcturus for good measure. Nice and pleasing way to enjoy the night sky w/out a scope.

#33 Jeff Lee

#34 monkeygodbob

Because no matter what, it's only me and the sky. I could have the worst day of my life, and if I can get out with the scopes, even for only a few minutes, it's the best day of my life.

Where else can you go and be completely and totally alone but in the middle of space. Especially out by my inlaws, where the only thing you hear is the crickets, and there's nothing but a billion stars and you. It's the only place you can go and be totally lost in a world without crime, and death, and crying babies, and honking horns, and bad people. It's the only place where no one expects anything of you, and you expect nothing of it, except the thrill of a stunning view. It's the only place where who you are and what you do doesn't matter. You don't need to worry about what the stars think of you, and they ask nothing of you except to be their companion for a while.

For me, it's the best end to another day on this planet. It's the best way for my anger and my stress to flow away. I used to use my Martial Arts, and meditation, to take me away from things, but astronomy has always been the one true thing to keep me sane.

You can't tell me that there isn't a single person who, if even for the first and only time, wasn't completely floored by their first real view through a telescope. There's still many times when I look through the eyepiece and can't believe it's me standing there seeing that.

It all sounds mushy and weird, and I make jokes about the money I spend and the things I do. But when it all comes down to the bare nuts and bolts, Astronomy is the only thing that you could do bad, and still have a genuinely great time.

Even if it's cloudy out, you can still enjoy it. You can wash and wax (hi Mark) your equipment. You can tinker with modifications, or rearrange your eyepiece case again.

You can even come here, to Cloudy Nights, and enjoy something wonderful with someone you've never met, but feel like you've known forever. You can finally find someone who enjoys astronomy the way you do, with your complete mind, heart, and soul.

And if that doesn't work, then how about this. Astronomy is the only hobby where you can sit out in public for hours on end with some of the most sinister looking equipment around, and not get into a heap of trouble.

I think he covered it there =-) It also gives me alot of time with my parents, and hopefully in the end it will introduce me into a future friend or girl friend along the way.. =D


So how does LIGO work?

The LIGO facility consists of two identical L-shaped detectors in Washington state and Louisiana, each of which employs lasers and mirrors to measure the tiny changes in spacetime made by passing gravitational radiation. The name of the game in each location is to record the change in distance between mirrors parked at each end of two perpendicular, 2.5-mile-long arms.

A laser bouncing back and forth between the mirrors keeps track of how far apart they are to an almost impossibly precise degree. Crucially, the detectors are sensitive to things such as passing trucks, lightning strikes, ocean waves, and earthquakes. For a signal to be real, it should show up in both detectors.

Now, the European Gravitational Observatory’s Virgo detector, which is similar to LIGO in design, is live. With three working observatories on the ground, scientists can more precisely identify the region on the sky where a gravitational wave source is located. Soon, similar experiments are anticipated to come online in Japan and India.


How would we know if Voyager 1 or 2 crashed into something?

I went to JPL's website, but there is nothing there about the possibility of it happening.

Did we just chose a course that at the time looked pretty empty to us?

We're still in contact with both so if that ceased unexpectedly then weɽ at least know something went wrong. More than likely itɽ have been some kind of failure on one of the crafts but knowing it had crashed into something would be pretty difficult to figure out. Perhaps if part of a spaceship was hit and the trajectory changed or it went into some kind of tumble then we might be able to deduce that it was hit.

In the long term though, space is pretty empty of large things that it could crash into. Or rather, space is so large that the chances of hitting those few things are incredibly slim, which has been discussed in previous questions before. So could it crash into something in the distant future way out there? Sure, it could. However, shutdown of the instruments will be on the timescale of a decade, so we wouldn't be able to tell after that anyway.


Galaxies hit single, doubles, and triple (growing black holes)

When three galaxies collide, what happens to the huge black holes at the centers of each? A new study using NASA's Chandra X-ray Observatory and several other telescopes reveals new information about how many black holes are furiously growing after these galactic smash ups.

Astronomers want to learn more about galactic collisions because the subsequent mergers are a key way that galaxies and the giant black holes in their cores grow over cosmic time.

"There have been many studies of what happens to supermassive black holes when two galaxies merge," said Adi Foord of Stanford University, who led the study. "Ours is one of the first to systematically look at what happens to black holes when three galaxies come together."

She and her colleagues identified triple galaxy merger systems by cross-matching the archives -- containing data that is now publicly available -- of NASA's WISE mission and the Sloan Digital Sky Survey (SDSS) to the Chandra archive. Using this method they found seven triple galaxy mergers located between 370 million and one billion light years from Earth.

Using specialized software Foord developed for her Ph.D. at the University of Michigan in Ann Arbor, the team went through Chandra data targeting these systems to detect X-ray sources marking the location of growing supermassive black holes. As material falls toward a black hole, it gets heated to millions of degrees and produces X-rays.

Chandra, with its sharp X-ray vision, is ideal for detecting growing supermassive black holes in mergers. The associated X-ray sources are challenging to detect because they are usually close together in images and are often faint. Foord's software was developed specifically to find such sources. Data from other telescopes was then used to rule out other possible origins of the X-ray emission unrelated to supermassive black holes.

The results from Foord and the team show that out of seven triple galaxy mergers there is one with a single growing supermassive black hole, four with double growing supermassive black holes, and one that is a triple. The final triple merger they studied seems to have struck out with no X-ray emission detected from the supermassive black holes. In the systems with multiple black holes, the separations between them range between about 10,000 and 30,000 light years.

"Why do we care about the hitting percentage of these black holes?" said co-author Jessie Runnoe of Vanderbilt University in Nashville, Tenn. "Because these statistics can tell us more about how black holes and the galaxies they inhabit grow."

Once they found evidence for bright X-ray sources as candidates for growing supermassive black holes in the Chandra data, the researchers incorporated archival data from other telescopes. Like a second umpire conferring about the original call, these data backed up the idea that multiple black holes were present in the merged galaxies.

To make these calls the authors studied infrared data from the WISE mission, the Infrared Astronomical Satellite, and the Two Micron All Sky Telescope to see how quickly stars are forming in the different galaxies in their survey. This allowed them to estimate how many of the detected X-rays are likely to come from X-ray emitting systems containing massive stars, rather than a growing supermassive black hole. Because such star systems are young they are more common when stars are forming more quickly. Foord and her colleagues used this technique to conclude that one of the X-ray sources they found is likely from a collection of X-ray emitting star systems.

The Chandra and WISE data show that the system with growing supermassive black holes has the largest amount of dust and gas. This matches theoretical computer simulations of mergers that suggest higher levels of gas near black holes are more likely to trigger rapid growth of the black holes.

Studies of triple mergers can help scientists understand whether pairs of supermassive black holes can approach so close to each other that they make ripples in spacetime called gravitational waves. The energy lost by these waves will inevitably cause the black holes to merge.

The Laser Interferometer Gravitational Wave Observatory (LIGO) and Virgo array in Europe have shown astronomers that stellar-mass black holes create gravitational waves and merge, but it is not known if supermassive black holes do.

"There is a "nightmare scenario" where supermassive black holes cannot lose enough energy to come close together and make gravitational waves" said co-author Michael Koss of Eureka Scientific in Oakland, California. "If this is the case then projects like LISA and pulsar timing arrays won't have any supermassive black hole mergers to detect."

However, gravitational interactions from a third supermassive black hole may prevent this stalling process. Studies of supermassive black holes in systems where three galaxies are merging are therefore important for understanding whether the nightmare scenario might apply.

The system with three growing supermassive black holes had previously been reported by Ryan Pfeifle of George Mason University in Fairfax, Virginia in a Chandra press release and an October 2019 paper in The Astrophysical Journal, and a team led by Xin Lui of the University of Illinois at Urbana-Champaign in a December 2019 paper in The Astrophysical Journal. This latest result helps put that discovery into context of other triple mergers of galaxies.

Foord presented the new study at the 237th meeting of the American Astronomical Society, which is being held virtually from January 11-15, 2021. Two papers describing this work have recently been accepted for publication in The Astrophysical Journal.

The Infrared Astronomical Satellite is a joint venture of NASA and its counterparts in the Netherlands and the UK, and the Two Micron All Sky Telescope is a collaboration between the University of Massachusetts and NASA's Infrared Processing and Analysis Center.

NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center controls science from Cambridge Massachusetts and flight operations from Burlington, Massachusetts.


Black Holes

Charles, P. & Wagner, R. &ldquoBlack Holes in Binary Stars: Weighing the Evidence.&rdquo Sky & Telescope (May 1996): 38. Excellent review of how we find stellar-mass black holes.

Gezari, S. &ldquoStar-Shredding Black Holes.&rdquo Sky & Telescope (June 2013): 16. When black holes and stars collide.

Jayawardhana, R. &ldquoBeyond Black.&rdquo Astronomy (June 2002): 28. On finding evidence of the existence of event horizons and thus black holes.

Nadis, S. &ldquoBlack Holes: Seeing the Unseeable.&rdquo Astronomy (April 2007): 26. A brief history of the black hole idea and an introduction to potential new ways to observe them.

Psallis, D. & Sheperd, D. &ldquoThe Black Hole Test.&rdquo Scientific American (September 2015): 74&ndash79. The Event Horizon Telescope (a network of radio telescopes) will test some of the stranger predictions of general relativity for the regions near black holes. The September 2015 issue of Scientific American was devoted to a celebration of the 100th anniversary of the general theory of relativity.

Rees, M. &ldquoTo the Edge of Space and Time.&rdquo Astronomy (July 1998): 48. Good, quick overview.

Talcott, R. &ldquoBlack Holes in our Backyard.&rdquo Astronomy (September 2012): 44. Discussion of different kinds of black holes in the Milky Way and the 19 objects known to be black holes.

Gravitational Waves

Bartusiak, M. &ldquoCatch a Gravity Wave.&rdquo Astronomy (October 2000): 54.

Gibbs, W. &ldquoRipples in Spacetime.&rdquo Scientific American (April 2002): 62.

Haynes, K., & Betz, E. &ldquoA Wrinkle in Spacetime Confirms Einstein&rsquos Gravitation.&rdquo Astronomy (May 2016): 22. On the direct detection of gravity waves.

Sanders, G., and Beckett, D. &ldquoLIGO: An Antenna Tuned to the Songs of Gravity.&rdquo Sky & Telescope (October 2000): 41.


Virtual Program: Listening to colliding black holes at the edge of the Universe

Join us on Wednesday , September 23 for a virtual program : Listening to colliding black holes at the edge of the Universe, a discussion featuring Daniel Holz and Vicky Kalogera , a nd m oderated by Cyndi Conn .

When: Wednesday, September 23 , 2020
1 2 p m Central

The LIGO and Virgo detectors are able to &ldquohear&rdquo in gravitational-waves the collisions of neutron stars and black holes &ndash confirming Einstein&rsquos predictions from a century ago. The ability to listen to gravitational waves opens up an entirely new and exciting window on the Universe and &ldquorewrites what we know about our universe&rdquo according to a New York Times article published earlier this month .

Daniel Holz , a member of the LIGO Virgo collaborative , is a professor at the University of Chicago in the Departments of Physics, Astronomy & Astrophysics, the Enrico Fermi Institute, and the Kavli Institute for Cosmological Physics and a member of the Bulletin&rsquos Science and Security Board.

Vicky Kalogera , a member of the LIGO Virgo collaborative , is the Daniel I. Linzer Distinguished University Professor in the Department of Physics & Astronomy and director of the Center for Interdisciplinary Exploration and Research in Astrophysics at Northwestern University.

Cyndi Conn is a member of the Bulletin&rsquos Governing Board and the Executive Director of Creative Santa Fe.


Why do &ldquothey&rdquo portray colliding black holes like that? - Astronomy

I have read about two black holes that will collide in a few hundred years. How will this affect Earth!

You have obviously read an article about the two black holes which are believed to exist in the central region of the galaxy NGC 6240 which is 140 million light years from us (for example this one from the NY Times). It has long been suspected that the nucleus of this galaxy might hold two black holes, and recent Chandra observations claim to have proven this to be the case. The black holes are in orbit around each other and as such will collide, however not for approximately a 100 million years (definitely not in a few hundred years). Black hole mergers may be happening all the time in external galaxies with no noticeable effects on Earth, therefore it is unlikely that this event will affect Earth at all.

This page was last updated on June 27, 2015.

About the Author

Karen Masters

Karen was a graduate student at Cornell from 2000-2005. She went on to work as a researcher in galaxy redshift surveys at Harvard University, and is now on the Faculty at the University of Portsmouth back in her home country of the UK. Her research lately has focused on using the morphology of galaxies to give clues to their formation and evolution. She is the Project Scientist for the Galaxy Zoo project.


Watch the video: Τι Θα Συμβεί Αν Ένας Μετεωρίτης Πέσει Στη Γη; (July 2022).


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