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Overweight galaxies force-fed by dark matter tendrils

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posted on Apr, 9 2009 @ 12:50 AM
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Some of the biggest galaxies in the early universe seem to have grown quicker than thought possible and may have bulked up on streams of gas flowing along filaments of dark matter, say researchers.

Monster galaxies have long been thought to take a long time to form, growing slowly by gobbling up smaller galaxies like a giant amoeba absorbing food.

But overeating in this way cannot explain why some of the brightest galaxies at the heart of five clusters dating from relatively soon after the big bang – more than 8 billion years ago – grew so large, so fast, according to new research performed using the Subaru telescope in Hawaii.

Models suggest that if they snacked only on other galaxies, those ancient leviathans should have been just a fifth as massive as the biggest galaxies in similar clusters today that have had longer to eat their smaller neighbours. But instead the ancient galaxies appear to be roughly 90 per cent as massive as their present-day counterparts.

"It could be the tip of the iceberg. It might mean the simulations [of the early universe] need to be significantly altered," says Chris Collins of Liverpool John Moores University in Birkenhead, UK.




Well it looks like we are constantly learning more and more about "dark matter".Thought this would interest some members on here so I posted it.I think the real question is why can't we see dark matter?So do any of you have opinions on dark matter?The usual sides are either "it is really some kind of 'dark',non visible matter"or it is a term for our ignorance and as some say the "Big Bang theory is wrong.Opinions?
newscientist.com




posted on Apr, 9 2009 @ 01:24 AM
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Dark matter was originally postulated as a means of accounting for oddities in the motion of stars in their galaxies. In order for them to be moving as fast as they are there would need to be more gravitational force than could be accounted for by the visible matter in the galaxy (stars, gas, dust). To avoid messing around with General Relativity, there had to be something which was bending space but was not visible. Dark matter. "Dark" because it does not seem to emit or absorb electromagnetic radiation. "Matter" because it would have same gravitational properties as the "normal" stuff we are used to.

In 2006 X-ray observations and mapping of gravitational lensing in the Bullet Cluster (a collision of two galactic clusters) made a very strong case for the actual existence of Dark Matter. There is something there which bends space but does not affect electromagnetic radiation. There is gravitational lensing but there is nothing "visible" where the lensing is occurring. There is nothing emitting radiation, nor absorbing it, in the areas where space is being bent and in turn, causing light from galaxies beyond to appear to bend. Dark matter. It is so far only detectable through mathematics and how it affects the space around it.

I sure as hell don't what it is or what other properties it may have. But it sure is a nice example of a hypothesis turning into a testable theory which is then tested.

blogs.discovermagazine.com...

[edit on 4/9/2009 by Phage]



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