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bberg
2007-Nov-01, 03:46 PM
If we assume that a massive black hole in the center of all (most) galaxies, and we know that black holes are collpsed stars, then can we assumes that the univserse was once made up of super giant stars that collapsed to form the galaxies we see today? this might be a stupid question, one that is more rhetorical, but it just came through my mind, so i decided to post it.

antoniseb
2007-Nov-01, 03:56 PM
You can't assume that *all* black holes are collapsed stars. The giant black holes in the centers of galaxies might have started off as very large stars, or they might have been something different. We might know the answer to this in our lifetimes, but we don't know now.

Fortunate
2007-Nov-01, 04:12 PM
I don't think we know how many of the supermassive black holes formed. We speculate some possible mechanisms. Accretion by an originally stellar-mass black hole is not the only conceivable possibilty - maybe not even the most likely one. See section under heading "Formation" in the following link:

http://en.wikipedia.org/wiki/Supermassive_black_hole


Black holes of this size can form in several ways....

I am sure that some other people here know more about this than I do, and I would love to hear their comments - I just thought I'd start the ball rolling.

John Mendenhall
2007-Nov-01, 05:01 PM
I am sure that some other people here know more about this than I do, and I would love to hear their comments - I just thought I'd start the ball rolling.



I feel the same way. Here's another good Wiki link.

http://en.wikipedia.org/wiki/Fundamental_plane_%28elliptical_galaxies%29

My hunch (usually worthless) is that supermassive black holes are primordial, but I have no idea how they originated.

Cougar
2007-Nov-01, 05:34 PM
If we assume that a massive black hole in the center of all (most) galaxies, and we know that black holes are collpsed stars, then can we assumes that the univserse was once made up of super giant stars that collapsed to form the galaxies we see today? this might be a stupid question, one that is more rhetorical, but it just came through my mind, so i decided to post it.
Early structure formation is one of the greatest unsolved problems in astrophysics today.

Tim Thompson
2007-Nov-01, 06:03 PM
It's a pretty good bet that the first generation of stars in the universe were indeed rather more massive than we see in the universe today. That's because the first generation of stars must form out of the hydrogen & helium produced in the Big Bang, whereas today's stars form out of gas that is polluted with heavy elements (carbon, oxygen & etc.). The presence of even small amounts of heavy elements changes the thermodynamics, and allows for the formation of much smaller stars. So the infant & early universe probably was dominated by supermassive stars (i.e., Bromm & Larson, 2004 (http://adsabs.harvard.edu/abs/2004ARA%26A..42...79B) although Silk & Mathieu, 2006 (http://adsabs.harvard.edu/abs/2006MNRAS.371..444S) disagree). But in the case of stars, supermassive means something like 1000 solar masses, not likely more. The supermassive galactic black holes have masses that range roughly from 1,000,000 to 1,000,000,000 solar masses. So they require a different evolutionary history to form.

We do not know how such supermassive black holes form in detail, but we have a pretty good idea of what happens in general. The easiest way to make such black holes is by merging galaxies together. This makes sense physically, and is consistent with the idea that masive galaxies form by the merger of smaller galaxies. The result of such a merger is the accretion by gravitational instability of matter into the core of the merged galaxy. That matter can accrete into a supermassive black hole fairly quickly, whether or not there is a black hole present to begin with (i.e., Duschl & Strittmatter, 2005 (http://adsabs.harvard.edu/abs/2005tmgm.meet..550D); Duschl & Strittmatter, 2006 (http://adsabs.harvard.edu/abs/2006astro.ph..2009D); Lodato & Natarajan, 2006 (http://adsabs.harvard.edu/abs/2006MNRAS.371.1813L)). There is a now well known relationship between the mass of the central supermassive black hole and the velocity dispersion of the stars in the galactic bulge, for spiral galaxies. In otherwords, the speed the stars move with depends on the mass of the black hole. But the stars are way too far from the black hole for that to have anything to do with a direct gravitational link between them. So the implication is that most of the mass in the black hole does not come from the original black hole, but rather from the material that has accreted onto it (i.e., Mahmood, Devriendt & Silk, 2005 (http://adsabs.harvard.edu/abs/2005MNRAS.359.1363M)).

The references link to the NASA ADS (http://www.adsabs.harvard.edu/) system, which allows you to follow the papers which cite the ones reference. If you follow the arXiv (http://arxiv.org/) eprint link, you can usually download PDF or PS of the original papers.

closetgeek
2007-Nov-02, 10:35 PM
From someone thoroughly uneducated[meaning me not you], I don't think it is a stupid question. It shows that you are seeking patterns which, to the best of my knowledge, is the ultimate beginning of science. It better not be a stupid question, I asked it a few months ago. :whistle: It seems to make the most sense.


If we assume that a massive black hole in the center of all (most) galaxies, and we know that black holes are collpsed stars, then can we assumes that the univserse was once made up of super giant stars that collapsed to form the galaxies we see today? this might be a stupid question, one that is more rhetorical, but it just came through my mind, so i decided to post it.

Michael Noonan
2007-Nov-03, 12:45 AM
Early structure formation is one of the greatest unsolved problems in astrophysics today.

Seeing as it is an unsolved mystery surrounding early structure formation what about a few thoughts on a simplest possible model?

What would happen to a sufficiently large ball of energy inflating that was not also creating its own space.

No this is not to disprove BBT, just a simplest thought exercise, could structure form as it expanded and cooled in:-
A static non moving reference
A moving reference

Fortunate
2007-Nov-03, 02:17 PM
If we assume that a massive black hole in the center of all (most) galaxies, and we know that black holes are collpsed stars....

I was browsing through some previous thread titles and realized that one of the those threads - a rather recent one, in fact - directly addressed a facet of the OP of this thread.

Never a Star: Did Supermassive Black Holes Form Directly? (http://www.bautforum.com/universe-today-story-comments/64354-never-star-did-supermassive-black-holes-form-directly.html)

EvilEye
2007-Nov-04, 03:10 AM
Haven't read the other thread.... but is this possible?

The "first in line" idea (not theory yet)

A super-massive black hole formed, and grew (massively) collecting dust and stuff.... and created the galaxies... but any other black hole that formed within that galaxy could never "outmass" the one at the center.

If that happened, we would see galaxies that are twisting within themselves.


Am I way off here?