Ultra-massive black holes, which lurk in the centers of huge galaxy clusters like the one above, seem to have an upper mass limit of 10 billion times that of the Sun. (Credit: NASA)

Black Holes Can Only Get So Big

5 Sep , 2008 by

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Black holes are thought to exist throughout the universe, with the largest and most massive found at the centers of the largest galaxies. These supermassive black holes have been shown to have masses upwards of one billion times that of our own Sun. But an astronomer studying black holes says there’s an upper limit to how big a black hole can get. Priyamvada Natarajan, an associate professor of astronomy and physics at Yale University has shown that even the biggest of these gravitational monsters can’t keep growing forever. Instead, they appear to curb their own growth – once they accumulate about 10 billion times the mass of the Sun.

These ultra-massive black holes, found at the centers of giant elliptical galaxies in huge galaxy clusters, are the biggest in the known universe. Even the large black hole at the center of our own Milky Way galaxy is thousands of times less massive than these behemoths. But these gigantic black holes, which accumulate mass by sucking in matter from neighboring gas, dust and stars, seem unable to grow beyond this limit regardless of where – and when – they appear in the universe. “It’s not just happening today,” said Natarajan. “They shut off at every epoch in the universe.”

Natarajan’s study is the first time an upper mass limit has been derived for black holes. Natarajan used existing optical and X-ray data of these ultra-massive black holes to show that, in order for those various observations to be consistent, the black holes must essentially shut off at some point in their evolution.

Artist's conception of a black hole.  Credit:  U of Tel Aviv

Artist's conception of a black hole. Credit: U of Tel Aviv

One possible explanation, says Natarajan, is that the black holes eventually reach the point when they radiate so much energy as they consume their surroundings that they end up interfering with the very gas supply that feeds them, which may interrupt nearby star formation. The new findings have implications for the future study of galaxy formation, since many of the largest galaxies in the universe appear to co-evolve along with the black holes at their centers.

“Evidence has been mounting for the key role that black holes play in the process of galaxy formation,” said Natarajan. “But it now appears that they are likely the prima donnas of this space opera.”

Source: PhysOrg


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quantum_flux
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September 5, 2008 4:41 PM

Well this just opens all sorts of questions concerning the Big Bang then.

Jim
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Jim
September 5, 2008 4:08 PM

AFAIK it’s hardly possible for two black holes to consome eachother, they rather attract eachother untill the bigger one repels the smaller one from the host galaxy in a renegade escape.

quantum_flux
Member
September 5, 2008 11:14 PM

I wonder if Black Holes can diverge or split?

td
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td
September 5, 2008 4:59 PM

it is possible for two black holes to merge…this is one of the main locations that “we” hope to detect gravitational waves…

Chuck Lam
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Chuck Lam
September 6, 2008 8:58 AM

Hmm . . . how can a black hole radiate energy in any form if light can’t escape. How is it another part of the energy spectrum can? If nothing can escape the gravitational pull of a black hole, then why would there be an upper limit to its size or mass? Maybe in time, the universe might evolve into an infinitely large black hole. Natarajan’s study of black hole radiation interference with the consumption of matter appears to be flawed.

Ziggy66
Member
Ziggy66
September 6, 2008 3:41 AM

“I wonder if Black Holes can diverge or split?”

Maybe in a collision of two of these upper limit black holes one of them could be split in two?
That would be awesome! If we don’t see gravity waves from something like that…

simon
Member
simon
September 6, 2008 6:20 AM

What kind of mechanism could split a black hole in two?

Surely an ultra massive black hole could still get bigger in collisions with other black holes moving at high speed towards each other.

Though I can see why it would not get bigger from absorbing stars, sort of a photoevaporation effect only for black holes instead of stars.

tomS
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tomS
September 6, 2008 7:52 AM

Seems to me I read many eons ago that black holes radiated (due to zero-point energy in space and virtual particles) and that the smaller they got the greater the radiation. When they got small enough, the would explode leaving nothing.

This implies that there is greater radiation from larger black holes. Does this contradict the above? Is the above still true?

Thanks,

Tom

Matthias
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Matthias
September 6, 2008 12:03 PM
@Chuck Lam: It’s called Hawking Radiation. basically, particle-anti particle pairs form spontaneously; sometimes one gets sucked in and the other escape; due to conservation of energy (=mass) what it carries away is taken from the black hole @tomS This process is connected to the tidal forces near the event horizon, and therefore is actually stronger, the smaller a black hole is. That’s why those they hope to make at the LHC won’t do any harm, as they will radiate away within fractions of a second. There is a “magical barrier”. If a black hole manages to grow beyond a certain size it will absorb more energy from the cosmic microwave background than it radiates away; i.e. any black… Read more »
Star Geezer
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Star Geezer
September 6, 2008 12:41 PM

I’m glad we cleared that urrrp!!…. I mean up… So I can continue to feed until I’ve consumed – or merged with… other black holes… then space.. .dark matter…dark energy… time…

Yum.

David
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David
September 6, 2008 12:53 PM

I have also read that black holes can radiate energy.
In this case though, I wonder if the observed limit to the growth of black holes could just be a natural part of the lifecycle of black holes and their surroundings. In other words, new physics, associated with super massive black holes, may not be needed to explain the observation.

bob
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bob
September 6, 2008 2:11 PM

No, this is NOT the first time someone has put an upper size limit on black holes. Amy Barger and Lennox Cowie drew the same reasoning about 3 years ago.

http://starbulletin.com/2005/02/17/news/story8.html

dennis
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dennis
September 7, 2008 6:29 AM

Duh- Conservation of energy? it can neither be created nor destroyed, therefore it cannot leave behind nothing.Given the velocity of moving black holes, the odds of it’s energy repelling an oncoming supermassive black hole are slim- THe 2 must collide and create a massave wave of some sort of energy and moswt likely massive quantities of particles. particles

Chris Coles
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September 7, 2008 7:42 AM

The fact is there is a complete misunderstanding of the actual structure of any mass object, not just the black hole. But you will all have to wait for a little longer to read more.

Maddad
Member
September 7, 2008 4:48 PM
The article raises two separate but related questions. One is why we have not observed ultramassive black holes more massive than about 10 billion solar masses. The second issue is whether there is a reason, a law of physics, which forbids a supermassive black hole from growing greater than this observation. Priyamvada Natarajan answered the first one well; we have not seen a more massive object. However, he misses on the second. The idea that energy radiation disrupts further growth of an ultramassive black hole is lame. That radiation results because the object grows. If it stops growing, then it stops radiating. There is now no reason for it not to start growing again. One problem is that… Read more »
LLDIAZ
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LLDIAZ
September 8, 2008 8:42 AM

It seems reasonable. I mean if it were’nt so the universe would be littered with black holes, something must be keeping them in check. The universe could not have let these “behemoths” grow unchecked for so long it would (eventually with enough time)swallow everything.

John in Missouri
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John in Missouri
September 8, 2008 6:38 AM
Okay, if I’m reading this right, what Professor Natarajan is really saying is not that a black hole can grow no larger than XXX, but that the mechanics of normal growth of a black hole prevent it from getting fed once its reached XXX level of massiveness, which is not the same. What if an extreme condition arises, say a small black hole, not really affected by normal interstellar pressures, wanders by close enough to be attracted to the big guy. if it approaches at the right angle and speed can’t it still be consumed? Another possibility; is it possible that at mass XXX consumption of whatever the universe throws at the black hole is so negligible compared… Read more »
astrobob
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astrobob
September 8, 2008 7:55 AM

Why didn’t the universe collapse into a black hole right before the big bang?

Starman
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Starman
September 10, 2008 5:27 PM
W’r ll gnn d vntlly. t’s jst mttr f whn. I’ve never understood how Hawking Radiation would work. I mean, don’t matter and anti-matter behave in a similar way under gravity? That being the case, when a particle pair spontaneously appears near a black hole’s event horizon, it’s gonna be a 50-50 chance as to which one of the particles falls in. If the matter particle fell in, the black hole would gain mass. On the other hand, if the anti-matter particle fell in, it would cancel some of the matter inside the black hole, so the black hole would lose mass. If the two processes have an equal chance of happening, there should be no overall effect… Read more »
willie
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willie
September 30, 2008 7:17 AM

Maybe my Karate chop.

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