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Old 04-24-2012, 09:07 AM
 
Location: Texas
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Ah!!! I forgot about the Great Attractor.
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Old 04-24-2012, 10:04 PM
 
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Quote:
Originally Posted by Glitch View Post
I agree that it is more likely that super massive black holes start out as ordinary stellar black holes, and then bulk up on the matter (and other smaller black holes) in their vicinity. I cannot conceive of another way to obtain the immense pressure required to form a black hole, but that could just be a lack of imagination on my part.
While I agree that supermassive black holes grow from matter as well as smaller black holes, there have been questions raised about the giants. Some may indeed have had a start from stellar black holes, but it's also possible black holes (at least some) could have originated from the Big Bang, before any of the first stars formed. During the early stage of Expansion, and possibly the earlier period of Inflation, conditions would have been incredibly chaotic from the hot soup of particles forming not to mention collisions between matter and antimatter. Although the universe would have still been relatively small, there would likely have been temperature variations. It's not too hard to imagine swirls of gas and particles forming that may well have been the beginning of what would ultimately become small proto black holes. As they attracted more material then they could consume, particles could have compressed enough to form some of the first stars, which in turn grouped together in galaxies.

That's not to dismiss the role of stellar mass black holes though. Nearly all galaxies are thought to contain a supermassive black hole. As far as I know, stellar mass black holes are thought to originate from supernovae. Even if supermassive black holes were originally stellar mass black holes, it raises an interesting question. Were there no black holes prior to the formation of the first stars? Sort of the chicken and the egg paradox.

We know that the gravitational force of black holes exerts the strongest gravitational attraction known in the universe and are enormously important in helping form the structures in the universe. It's a pretty good guess that gravity in the beginning stages of the universe was much stronger than it is today, although not strong enough to counter the expansion of the Big Bang itself. The collision of particles could well have been the start of some black holes that were big enough and survived long enough to begin consuming material and continue growing. As the expansion of the universe continued, the collisions between particles would have become fewer as things became more spread out. But there still would have be enough material around for black holes to feed and grow, and by attracting material, particles were compressed and dense enough to ultimately form the first stars that explode generating new particles by stellar nucleosynthesis and scattering the material out into space and away from the black holes.

Generally speaking, it seems like the consensus about black holes is that the origins of stellar mass black holes and supermassive black holes may be different. The beginning of what have now become supermassive black holes may have originated from the extreme density of the universe during inflation well before the formation of stars.

Admittedly, I have no idea if such a scenario is right or not though.


Quote:
I would suggest that the pair of super massive black holes in NGC 3393 have not formed a bar because of their proximity to each other and the difference in size. Although they do not mention the size of each of these super massive black holes in NGC 3393, they do describe it as a "minor" collision or merger and that these two super massive black holes are only 490 light years apart. If one super massive black hole is substantially smaller than another, it is possible for the larger super massive black hole to absorb the smaller without being disturbed. I suspect barred spiral galaxies are formed when two galaxies with super massive black holes of roughly equal mass collide or merge. Particularly since these two roughly equally massed black holes will be rotating around a common barycenter.
I see what you mean and you may be right regarding a pair of black holes of similar size. Still, a distance of 490 light years between them is pretty darned close. There might be another factor involved as well. Andromeda is a gigantic galaxy with a population of about one trillion stars. The Milky Way is smaller with a population of 200-400 billion stars. The difference between the two galaxies is that it's thought the density of the Milky Way may be greater than that of Andromeda. Perhaps the density of the Milky Way has contributed to conditions for it to have become a barred galaxy?


Quote:
If Canis Major is not a dwarf galaxy, then the other dwarf galaxy that is currently colliding with the Milky Way is the Sagittarius Dwarf elliptical galaxy. It also is being ripped apart by tidal forces and being absorbed by the Milky Way.

Source: Sagittarius Dwarf Elliptical Galaxy / SagDEG
I agree.


Quote:
I am looking forward to the event.
Best wishes. I know I won't be around long enough to see the collision.


Some interesting vids you might enjoy. The first one is a look at the hole in the Andromeda galaxy. This one was thought to have been created from the M32 Dwarf galaxy that plowed through it. Tony Darnell makes some excellent presentations. A great speaker.

The second vid is more of an extended version of the one you posted. The music to it is kind of funky. One of the tunes sounds like it's from Jurassic Park. But the galactic collision simulation is interesting.

The third is from Space Rip who presents an excellent collection. This one is another look at the collision.

I think as we better understand the nature of such galactic event, we might also better understand a little bit about the nature of Dark Matter and how it too shapes and interacts with galaxies. During such collisions, Dark Matter would certainly seem to enter the interior of galaxies, but might ultimately end up around the exterior as the colliding galaxies settle down.



The Hole in the Andromeda Galaxy - YouTube



Andromeda/Milky Way collision (simulation) - YouTube



A Look at the Milky Way's Future - YouTube
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Old 04-24-2012, 10:44 PM
 
Location: Texas
5,070 posts, read 9,078,959 times
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Quote:
Generally speaking, it seems like the consensus about black holes is that the origins of stellar mass black holes and supermassive black holes may be different. The beginning of what have now become supermassive black holes may have originated from the extreme density of the universe during inflation well before the formation of stars.

Admittedly, I have no idea if such a scenario is right or not though.
I agree -- at least that is what my gut says.
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Old 04-25-2012, 12:57 AM
 
Location: Wasilla, Alaska
17,825 posts, read 20,504,794 times
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Quote:
Originally Posted by NightBazaar View Post
While I agree that supermassive black holes grow from matter as well as smaller black holes, there have been questions raised about the giants. Some may indeed have had a start from stellar black holes, but it's also possible black holes (at least some) could have originated from the Big Bang, before any of the first stars formed. During the early stage of Expansion, and possibly the earlier period of Inflation, conditions would have been incredibly chaotic from the hot soup of particles forming not to mention collisions between matter and antimatter. Although the universe would have still been relatively small, there would likely have been temperature variations. It's not too hard to imagine swirls of gas and particles forming that may well have been the beginning of what would ultimately become small proto black holes. As they attracted more material then they could consume, particles could have compressed enough to form some of the first stars, which in turn grouped together in galaxies.

That's not to dismiss the role of stellar mass black holes though. Nearly all galaxies are thought to contain a supermassive black hole. As far as I know, stellar mass black holes are thought to originate from supernovae. Even if supermassive black holes were originally stellar mass black holes, it raises an interesting question. Were there no black holes prior to the formation of the first stars? Sort of the chicken and the egg paradox.

We know that the gravitational force of black holes exerts the strongest gravitational attraction known in the universe and are enormously important in helping form the structures in the universe. It's a pretty good guess that gravity in the beginning stages of the universe was much stronger than it is today, although not strong enough to counter the expansion of the Big Bang itself. The collision of particles could well have been the start of some black holes that were big enough and survived long enough to begin consuming material and continue growing. As the expansion of the universe continued, the collisions between particles would have become fewer as things became more spread out. But there still would have be enough material around for black holes to feed and grow, and by attracting material, particles were compressed and dense enough to ultimately form the first stars that explode generating new particles by stellar nucleosynthesis and scattering the material out into space and away from the black holes.

Generally speaking, it seems like the consensus about black holes is that the origins of stellar mass black holes and supermassive black holes may be different. The beginning of what have now become supermassive black holes may have originated from the extreme density of the universe during inflation well before the formation of stars.

Admittedly, I have no idea if such a scenario is right or not though.
You make a very good point about the origins of super massive black holes having a different evolution than stellar black holes. Particularly in the early stages of the universe.

From what I have read there seems to be an upper limit on the size of Population I and II type stars of between 130 and 150 solar masses. But in the early universe there were also Population III type stars, comprised of only hydrogen and helium, and no metals. Those Population III type stars would have been much bigger than 150 solar masses. Some have estimated Population III type stars to be as much as 1,000 solar masses, or more. Unfortunately, there are no Population III type stars remaining, so we may never know just how big they became.

Population III type stars would have formed approximately 400 million years after the Big Bang and are credited for triggering the reionization process, but they would have only lived for a few million years at best.

Source: First Stars / Population III

Another form of stellar black hole we have recently discovered in nearby clusters occur when neutron star binaries collide. At the point of impact they theorize that binary neutron stars release a Gamma-Ray Burst, just before becoming a black hole with the combined mass of the two neutron stars.

I have difficulty comprehending how a black hole could have formed without a star. In order to achieve the pressures necessary to form a black hole the mass would have to be sufficient to generate temperatures in excess of 100 billion degrees kelvin. I do not know how you can get those kinds of temperatures without forming a very large star.

Quote:
Originally Posted by NightBazaar View Post
Some interesting vids you might enjoy. The first one is a look at the hole in the Andromeda galaxy. This one was thought to have been created from the M32 Dwarf galaxy that plowed through it. Tony Darnell makes some excellent presentations. A great speaker.

The second vid is more of an extended version of the one you posted. The music to it is kind of funky. One of the tunes sounds like it's from Jurassic Park. But the galactic collision simulation is interesting.

The third is from Space Rip who presents an excellent collection. This one is another look at the collision.

I think as we better understand the nature of such galactic event, we might also better understand a little bit about the nature of Dark Matter and how it too shapes and interacts with galaxies. During such collisions, Dark Matter would certainly seem to enter the interior of galaxies, but might ultimately end up around the exterior as the colliding galaxies settle down.
Thanks for the video links. There is so much that we do not understand, and that makes it an exciting time to be alive. Just last year a 10 year-old Canadian girl discovered a supernova. Just think what we can discover tomorrow.
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Old 04-25-2012, 01:13 PM
 
5,206 posts, read 8,210,851 times
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Quote:
Originally Posted by Glitch View Post
I have difficulty comprehending how a black hole could have formed without a star. In order to achieve the pressures necessary to form a black hole the mass would have to be sufficient to generate temperatures in excess of 100 billion degrees kelvin. I do not know how you can get those kinds of temperatures without forming a very large star.
You're right. There's a lot about the universe that's difficult to understand or comprehend. While I agree with your point about high temperatures and pressures, higher temperatures and pressures would have been present well before any stars were formed. Temperatures of the entire universe are estimated to have been around 1000 trillion (yep, that's trillion) degrees Celsius a tiny fraction of a second after the initiation of the Big Bang. The event of the Big Bang would have been far more extreme than anything in the universe. The pressure and temperature would have been truy mind-boggling. Nothing in the universe trumps the conditions of the Big Bang.

The CMB is thought to be the echo of the Big Bang. What we can see in the WMAP represent temperature differences, that now have expanded to enormous sizes because of the continued expansion of the universe. If we rewind or compress the view back to the early stages of the Big Bang, we'd likely find variations and fluctuations although so tiny it'd be hard to easily measure. Regardless, these fluctuations of matter in the early universe, black holes of any size could easily have formed (even before stars) and remained stable because of the density of matter in the conditions of such extreme temperature and pressure existing in the early universe. These black holes are called Primordial Black Holes.

Origins: CERN: Ideas: The Big Bang

Primordial black hole - Wikipedia, the free encyclopedia
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Old 04-25-2012, 01:47 PM
 
Location: Texas
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I'ts amazing that the CMB comes from every direction, just this trillion degrees Celsius is amazing.
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Old 04-25-2012, 03:11 PM
 
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Originally Posted by Brian.Pearson View Post
I'ts amazing that the CMB comes from every direction, just this trillion degrees Celsius is amazing.
More precisely, 1000 trillion (1 quadrillion) degrees. That'd be pretty toasty.

I should add that temps seen in the CMB are much cooler now.
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Old 04-25-2012, 05:20 PM
 
Location: Texas
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[quote=NightBazaar;24025128]More precisely, 1000 trillion (1 quadrillion) degrees. That'd be pretty toasty.

The word "toasty" doesn't quite do it service...
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Old 04-25-2012, 05:54 PM
 
Location: Wasilla, Alaska
17,825 posts, read 20,504,794 times
Reputation: 6500
Quote:
Originally Posted by NightBazaar View Post
You're right. There's a lot about the universe that's difficult to understand or comprehend. While I agree with your point about high temperatures and pressures, higher temperatures and pressures would have been present well before any stars were formed. Temperatures of the entire universe are estimated to have been around 1000 trillion (yep, that's trillion) degrees Celsius a tiny fraction of a second after the initiation of the Big Bang. The event of the Big Bang would have been far more extreme than anything in the universe. The pressure and temperature would have been truy mind-boggling. Nothing in the universe trumps the conditions of the Big Bang.

The CMB is thought to be the echo of the Big Bang. What we can see in the WMAP represent temperature differences, that now have expanded to enormous sizes because of the continued expansion of the universe. If we rewind or compress the view back to the early stages of the Big Bang, we'd likely find variations and fluctuations although so tiny it'd be hard to easily measure. Regardless, these fluctuations of matter in the early universe, black holes of any size could easily have formed (even before stars) and remained stable because of the density of matter in the conditions of such extreme temperature and pressure existing in the early universe. These black holes are called Primordial Black Holes.

Origins: CERN: Ideas: The Big Bang

Primordial black hole - Wikipedia, the free encyclopedia
Thanks for the links. I had heard of primordial black holes before, but still associated them with early star formation. It had not occurred to me that black holes could have formed prior to ionization. However, now that I have read the links that you provided I have a better understanding of how primodial black holes could form without a star.

Reading further on the subject, the black holes could have formed during the Hadron Epoch (from 0.000001 to 1 second after the Big Bang), when the temperature of the universe was still around 100 billion degrees kelvin. During the Lepton Epoch (from 1 to 10 seconds after the Big Bang) the universe had cooled down to "only" a billion degrees kelvin, which is not hot enough to form a black hole, much less a super massive black hole.

Therefore, it would appear that the pressure and temperature was sufficient to create black holes within the first second of the Big Bang, long before stars formed. Even before hellium formed during the Nucleosynthesis period (between 3 minutes and 20 minutes after the Big Bang).

I am going to have to think more on this before I can digest it completely.
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Old 04-26-2012, 07:59 PM
 
5,206 posts, read 8,210,851 times
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Quote:
Originally Posted by Glitch View Post
Thanks for the links. I had heard of primordial black holes before, but still associated them with early star formation. It had not occurred to me that black holes could have formed prior to ionization. However, now that I have read the links that you provided I have a better understanding of how primodial black holes could form without a star.

Reading further on the subject, the black holes could have formed during the Hadron Epoch (from 0.000001 to 1 second after the Big Bang), when the temperature of the universe was still around 100 billion degrees kelvin. During the Lepton Epoch (from 1 to 10 seconds after the Big Bang) the universe had cooled down to "only" a billion degrees kelvin, which is not hot enough to form a black hole, much less a super massive black hole.

Therefore, it would appear that the pressure and temperature was sufficient to create black holes within the first second of the Big Bang, long before stars formed. Even before hellium formed during the Nucleosynthesis period (between 3 minutes and 20 minutes after the Big Bang).

I am going to have to think more on this before I can digest it completely.
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
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