Why do galaxy clusters form sheets?

In summary, the conversation discusses the existence of galactic cluster sheets and the possible reasons for their formation. The participants suggest different theories such as collisions between galaxies, preferred spin of clouds, and chaotic behavior. They also mention the lack of mathematical models to fully explain this phenomenon.
  • #1
drag
Science Advisor
1,105
1
Greetings !

I just read Saint's post in the "moving galaxy"
thread and though I knew the answer to that, I do
not believe I have so far read somewhere an
explanation for the existence of the galactic
cluster sheets.

So, is there a known and recognized reason ?
(My guesses :
1. The same reason that star-systems and galaxies are
mostly two-dimensional - a simple kinematic
solution for a system of bodies enitially spread
around mostly at rest and mutually affected by
gravitational forces.
2. Some form of quantization during the BB ? )

Thanks.

"I sometimes ask myself how it came about that
I was the one to develop the theory of relativity.
The reason, I think, is that a normal adult
never stops to think about problems of space and time.
These are things which he has thought about as a child.
But my intellectual development was retarded, as a
result of which I began to wonder about space and time
only when I had already grown up."
Albert Einstein

Live long and prosper.
 
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  • #2
drag-

How about early galactic collisions and their spatial redistribution of angular momentum?

Also, sheet clusters may have evolved from clouds of preferred spin.

Your guesses are good ones, too!
 
  • #3
Greetings Loren !
Originally posted by Loren Booda
How about early galactic collisions and their
spatial redistribution of angular momentum?
You mean - shockwaves ?
Wouldn't expansion prevent that ?
Originally posted by Loren Booda
Also, sheet clusters may have evolved
from clouds of preferred spin.
What do you mean (matter & anti-matter)?
Originally posted by Loren Booda
Your guesses are good ones, too!
Thanks, but my first one does not explain why
the sheets are mostly parallel at all.
And my second is far from anything I could provide
an educated opinion about - just a wild thought.

Live long and prosper.
 
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  • #4
drag-

Collisions between galaxies of various orientations in the early universe may have enabled parallel distribution. Preferring low angular velocity, the developing galaxies expanded in one plane while conserving angular momentum and increasing entropy.

Before galaxies there were stars, and before them, hydrogen molecules. In a given primordial region much larger than a galaxy but much smaller than the universe there would have been probably an overall angular momentum which condensed eventually into local galactic sheets.
 
  • #5
Greetings !

Intresting.
Is this some type of Chaotic behaviour (there are
huge amounts of stars and matter in every "sheet") ?
Are there some mathematical models that adress
such a solution ? What's the difference if we
consider every star to be a galaxy and then
use the same model ? Do the "sheets" have angular
momentum (which could "help" such a model) ?

(Links would also be appreciated people, I'm going
to look for some myself too.)

Thanks !

Live long and prosper.
 
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  • #6
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