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Old 04-26-2012, 08:54 PM
 
Location: Texas
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Quote:
Originally Posted by NightBazaar View Post
Of course it probably took time for primordial black holes to develop into supermassive black holes. Below is a link to a short abstract on the subject. It was revised last month.

[1202.3848] Primordial seeds of supermassive black holes


If you have a PDF reader, this link should take you to the full paper.
http://arxiv.org/pdf/1202.3848v2.pdf
I'm not too clear about what supersymmetry is when talking about black holes --

"We have adopted a speci c model for double in ation in the present Letter. However, double or multiple-stage in ation is quite generic in supersymmetry and string theory, and in aton decays due to parametric resonance in preheating epochs between inflationary stages
are also common. Therefore, it can be expected that PBHs with a narrow mass distribution are produced in the inflationary universe. Besides the sharp peak in the density perturbation spectrum, double ination models generally predict a large running of the spectral index. For the smooth hybrid new in ation model we obtain 􀀀0:02 . (dns=d ln k) . 􀀀0:01, which can be tested in future CMB observations.
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Old 04-27-2012, 04:08 PM
 
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Originally Posted by Brian.Pearson View Post
I'm not too clear about what supersymmetry is when talking about black holes --

"We have adopted a speci c model for double in ation in the present Letter. However, double or multiple-stage in ation is quite generic in supersymmetry and string theory, and in aton decays due to parametric resonance in preheating epochs between inflationary stages
are also common. Therefore, it can be expected that PBHs with a narrow mass distribution are produced in the inflationary universe. Besides the sharp peak in the density perturbation spectrum, double ination models generally predict a large running of the spectral index. For the smooth hybrid new in ation model we obtain 􀀀0:02 . (dns=d ln k) . 􀀀0:01, which can be tested in future CMB observations.
Supersymmetry is pretty heady stuff as it gets beyond the Standard Model. You're not alone. I don't clearly understand it either. Maybe someone else can explain it better.

The thing about supersymmetry is that it's theoretical. There's been no hard evidence to support its existence. It's one of the theories that has been hoped the LHC would nail down to confirm it one way or the other. If supersymmetry can be confirmed, then it means things are on the right track toward the Theory of Everything. If not, then it would probably mean back to the drawing board to revise the Standard Model. As of last August, the LHC has not yet found any signs of supersymmerty. No confirmation of the Higgs boson either. Either these things are much more deeply hidden than had been expected, or they don't exist.
LHC Experiment Finds No Signs of Supersymmetry | Wired Science | Wired.com

My understanding of supersymmetry is that it's an extension of quantum physics. Connected with supersymmetry is quantum gravity, which in turn is part of the idea behind Primordial Black Holes (PBH). Another clue related to PBH is that a number of quasars in some of the oldest galaxies, energetic supermassive black holes, formed much earlier than previously thought. These things were already monsters near the beginning of the universe, and probably formed before there were any stars. If that's true, then it raises the question, how did they originate? PBH seem to be a likely candidates. Supersymmetry provides an explanation to the origins of PBH, and the idea of double or multiple inflation periods, and may very well get involve extra dimensions.
Supersymmetry - Wikipedia, the free encyclopedia

Quantum gravity - Wikipedia, the free encyclopedia

The connection of supersymmetry with black holes, might have to be qualified. For example stellar black holes seem to originated from the collapse of giant or supergiant stars which explode as supernovae. If some (maybe all) supermassive black holes had their origins as PBH, then I think they have evolved to develop physics that are a bit different. I'm really not clear on all this myself.

It's worth noting that a PBH could be small, maybe like a micro black hole, but there's nothing that requires to to be small. In a nutshell, the paper is looking at the possible origins of PBH.

I'll be brief, but you can check Parts II, III and IV in the paper again for the details. A lot of it gets pretty technical and hard to understand, but I think the gist of it gives an idea about it without fussing through all the math. If you can wade through all that, more power to you. I admit that it's hard to visualize the idea of two or more inflation periods. The way I understand it, it involves perturbations of the inflation connecting with an inflation field. It's in this area that supersymmetry may be thought to be involved. In any case, the PBH would have been able to absorb gas and produce ionizing X-ray radiation.

The bottom line being that the authors are inclined to think that PBH may have been the seeds of supermassive black holes in galaxies. Certainly Gravity and pockets of cooler temperatures in the CMB would come into play when stars began forming, ultimately being attracted, along with gas, to black holes to not only continue feeding the black holes, but to also begin the evolution and growth of galaxies. Images I've seen of early proto galaxies from the Hubble's Ultra Deep Field view show them to be pretty strange looking structures.

In Part IV, it says:
"While direct ionization is probably too weak to aff ect the optical depth measured by WMAP, the increase is signifi cant enough to enhance formation of molecular hydrogen, which is an important cooling agent needed for the collapse of gas clouds leading to formation of the first stars. WMAP constraints [42] allow for one supermassive primordial black hole per galaxy, as our model predicts."
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Old 04-27-2012, 08:22 PM
 
Location: Texas
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"If primordial black holes are the source of dark matter, the sheer number of stars in the Milky Way galaxy -- roughly 100 billion -- makes an encounter inevitable, the authors report. Unlike larger black holes, a primordial black hole would not "swallow" the star, but cause noticeable vibrations on the star's surface as it passes through."

Very curious behavior of PBHs. Curiouser and curiouser... A black hole containing Dark Matter is just plain weird.
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Old 04-27-2012, 10:14 PM
 
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Quote:
Originally Posted by Brian.Pearson View Post
"If primordial black holes are the source of dark matter, the sheer number of stars in the Milky Way galaxy -- roughly 100 billion -- makes an encounter inevitable, the authors report. Unlike larger black holes, a primordial black hole would not "swallow" the star, but cause noticeable vibrations on the star's surface as it passes through."

Very curious behavior of PBHs. Curiouser and curiouser... A black hole containing Dark Matter is just plain weird.
This link and the vid below includes the line of thought regarding the vibrations as a PBH passes through a star.
Primordial Black Holes, Dark Matter and Stellar Collisions… Oh, My!



Primordial Black Hole Passes Through Star - YouTube



And just when we all thought it was safe to go back into the water....

"In Einstein's theory of general relativity, which describes a universe with three dimensions of space (plus one of time), Hawking radiation would have caused all primordial black holes smaller than a few hundred million tons to evaporate by now. That could change, though, if the universe has more than three spatial dimensions."
NOVA | Tiny Black Holes
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Old 04-27-2012, 11:24 PM
 
Location: Wasilla, Alaska
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Quote:
Originally Posted by NightBazaar View Post
For example stellar black holes seem to originated from the collapse of giant or supergiant stars which explode as supernovae.
Neutron binaries are also capable of creating black holes. They are using this model in an attempt to explain GRBs. It is still theoretical of course, nobody has yet observed a collision between neutron binaries.

Quote:
"We're theorizing that the gamma-ray burst is not the observable effect from the collision of in-spiraling neutron binaries, but the result of heating and the subsequent neutrino-to-photon radiation process that occurs in a few brief seconds before such a collision," said Salmonson, an LLNL/U.C. Davis graduate student.

Source: Colliding neutron star binaries
Quote:
Originally Posted by NightBazaar View Post
It's worth noting that a PBH could be small, maybe like a micro black hole, but there's nothing that requires to to be small. In a nutshell, the paper is looking at the possible origins of PBH.
In 1974 Stephen Hawking theorized that all black holes give off a "black-body" particle radiation as a result of quantum effects near the event horizon. This "Hawking Radiation" would cause the black hole to slowly evaporate over time.

A small (smaller than 4.5 × 10^22 kg [about the mass of the moon]) PBH would emit more radiation than they absorb, thus losing mass.

Quote:
Originally Posted by NightBazaar View Post
The bottom line being that the authors are inclined to think that PBH may have been the seeds of supermassive black holes in galaxies. Certainly Gravity and pockets of cooler temperatures in the CMB would come into play when stars began forming, ultimately being attracted, along with gas, to black holes to not only continue feeding the black holes, but to also begin the evolution and growth of galaxies. Images I've seen of early proto galaxies from the Hubble's Ultra Deep Field view show them to be pretty strange looking structures.

In Part IV, it says:
"While direct ionization is probably too weak to affect the optical depth measured by WMAP, the increase is significant enough to enhance formation of molecular hydrogen, which is an important cooling agent needed for the collapse of gas clouds leading to formation of the first stars. WMAP constraints [42] allow for one supermassive primordial black hole per galaxy, as our model predicts."
I am not sure why they are thinking that PBHs must be "small" (smaller than 4.5 × 10^22 kg), which, as you pointed out, should have completely evaporated by now. The universe is not that consistent. I envision PBHs to be every conceivable size, from micro to super massive, and everything in between. As long as you have sufficient pressure and temperature, any amount of mass could be compressed into a black hole.

The Population III stars would have first formed 30 million years after the Big Bang. The first galaxies some 600 million years after the Big Bang. Considering that Population III stars would have lived for less than 10 million years, that is several dozen generations of stars that would have formed and died before galaxies formed.

However, PBHs could only have formed within the first second of the Big Bang. After that first second the universe would have been too cold for PBHs to form. We would have to wait another 30+ million years before the first stellar black hole could have been formed.

That would give PBHs around 600 million years to bulk up on other PBHs, stellar black holes, and the surrounding matter to become super massive and thereby start galaxy formation. I also think it is possible that there may have been super massive PBHs from the very beginning (within the first second after the Big Bang), just waiting for stars to eventually form so galaxy formation could begin.

I also think that some of the quasars we are seeing that date back to 13 billion years ago could be examples of super massive PBHs bulking up on the surrounding matter.

See http://dawn.com/2011/06/30/scientist...rliest-quasar/

Last edited by Glitch; 04-27-2012 at 11:46 PM..
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Old 04-28-2012, 01:23 AM
 
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Quote:
Originally Posted by Glitch View Post
Neutron binaries are also capable of creating black holes. They are using this model in an attempt to explain GRBs. It is still theoretical of course, nobody has yet observed a collision between neutron binaries.
That's possible. When unstable supergiant stars collapse, some can become black holes and some can become neutron stars. I agree, there has not been any observations of colliding binary pairs of neutron stars.


Quote:
In 1974 Stephen Hawking theorized that all black holes give off a "black-body" particle radiation as a result of quantum effects near the event horizon. This "Hawking Radiation" would cause the black hole to slowly evaporate over time.

A small (smaller than 4.5 × 10^22 kg [about the mass of the moon]) PBH would emit more radiation than they absorb, thus losing mass.
Hawking is right, although I think as long as there is sufficient matter being available and consumed by a black hole, it's not likely to evaporate out of existence for a very long time. Assuming that the universe will continue expanding indefinitely, the prediction is that long after the last star flickers out, the age of black holes will reign until they too finally evaporate out of existence.

I'm inclined to think the point about small black holes may apply to those in the current state of the universe. During the early universe though, when temperatures and density was profoundly extreme, a PBH might have had a hard time losing mass. As the fledgling universe continued expanding, PBHs may have had ample opportunity to rapidly increase in size from the abundance of hot gas surrounding it. Once the space of the universe was much larger and much cooler, the rapid growth of a PBH would likely start to slow down, but by then it would've reached a point to be at or near being the size of a SMBH.


Quote:
I am not sure why they are thinking that PBHs must be "small" (smaller than 4.5 × 10^22 kg), which, as you pointed out, should have completely evaporated by now. The universe is not that consistent. I envision PBHs to be every conceivable size, from micro to super massive, and everything in between. As long as you have sufficient pressure and temperature, any amount of mass could be compressed into a black hole.

The Population III stars would have first formed 30 million years after the Big Bang. The first galaxies some 600 million years after the Big Bang. Considering that Population III stars would have lived for less than 10 million years, that is several dozen generations of stars that would have formed and died before galaxies formed.

However, PBHs could only have formed within the first second of the Big Bang. After that first second the universe would have been too cold for PBHs to form. We would have to wait another 30+ million years before the first stellar black hole could have been formed.

That would give PBHs around 600 million years to bulk up on other PBHs, stellar black holes, and the surrounding matter to become super massive and thereby start galaxy formation. I also think it is possible that there may have been super massive PBHs from the very beginning (within the first second after the Big Bang), just waiting for stars to eventually form so galaxy formation could begin.

I also think that some of the quasars we are seeing that date back to 13 billion years ago could be examples of super massive PBHs bulking up on the surrounding matter.

See Scientists discover brightest, earliest quasar | DAWN.COM
The impression I got is that a PBH can be any size, including small. The video, if that's what you meant, was just meant as an example of the effect to a star if a smaller one passed through it.

If the source of a supermassive black hole (found at the center of most galaxies) is that it originated from a PBH, then my guess is that it was probably much smaller to begin with and grew to eventually become a SMBH. Whether PBHs still exist, or have ever existed, at the present time is unknown.

I agree that the universe isn't completely consistent. A look at images of the CMB shows that. There are areas that are warmer and areas that are cooler. That's worked out pretty well, or else we probably wouldn't be here talking about it.
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Old 04-28-2012, 12:43 PM
 
Location: Texas
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A bit off topic, but I was wondering why, when you see a star being sucked into a black hole, why does it turn into a disk? Have anything to do with the spin of the black hole? And of course there is the gamma ray stuff perpendicular to the disk.

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Old 04-28-2012, 02:07 PM
 
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It is just easier to believe the evidence - there is no 'dark matter' and no 'black holes.' Plasma and/or electric models explain things better.
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Old 04-28-2012, 03:02 PM
 
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Default Back To Square One?

The controversy over the absence of Dark Matter our stellar the neighborhood of the galaxy, which includes our own solar system, may be turning around once again. According to a recent article in Space.com, theoretical Ann Freese disagrees with the finding that Dark Matter seems to be missing in our region near the Sun.
Quote:
Though recent research has suggested that our corner of the universe is actually not bathed in dark matter, Freese did not find this work compelling. "The stars they looked at are 1.5 to 4 kiloparsecs (4,892 to 13,046 light years) below the galactic plane — nowhere near the sun," Freese said. "I wouldn't trust their extrapolation to the solar neighborhood, which relies on a lot of assumptions."
Dark Matter might not be 'missing' after all all.

Dark Matter May Collide With Atoms Inside You More Often Than Thought | Dark Matter Human Body Collisions | Space.com
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Old 04-28-2012, 07:32 PM
 
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Originally Posted by Brian.Pearson View Post
A bit off topic, but I was wondering why, when you see a star being sucked into a black hole, why does it turn into a disk? Have anything to do with the spin of the black hole? And of course there is the gamma ray stuff perpendicular to the disk.
There are a couple of different types of black holes. Kerr, which rotate and Schwarzschild, which do not rotate. Kerr black holes form an accretion disk that follows the spin of the black hole. They can also produce powerful polar jets. If a star, or anything else, gets close enough, the gravitational attraction of the black hole begins to pull in, literally stripping, the outer layers of the star. As the material from the star is stretched and pulled in toward the black hole, it is pulled into the rapidly rotating accretion disk which then draws it closer to the event horizon.

If stars are close enough to be affected by the black hole's gravitational pull, but far enough to not be pulled into the accretion disk, then the stars can orbit the black hole. The speed at which the stars can orbit is incredibly fast, and stars seem to be able to travel around the black hole in all sorts of eccentric paths.

Schwarzschild black holes have no spin and therefore have no accretion disk and no polar jets. They can attract and pull in material from any direction.
HowStuffWorks "How Black Holes Work"

Here are a couple of interesting and worthwhile vids on the subject of the Milky Way's supermassive black hole. The first one is about the discovery and confirmation of the galaxy's monster. There are some very interesting views showing stars orbiting an invisible and supermassive monster. The second one is about the recent discovery of a hydrogen gas cloud that is being stretched apart and pulled into the black hole. The cloud probably won't make a direct hit, but will orbit extremely close, close enough to pull in a lot of material, stretching it out like a piece of taffy. Even though the cloud is expected to pull away from the black hole, it might not be able to fully escape. If it can, it'll still be quite a mess.


Supermassive Black Hole in the Milky Way Galaxy - YouTube



Supermassive Black Hole Vacuums Up a Huge Gas Cloud - YouTube
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