The Mudcat Café TM
Thread #70797 Message #1424923
Posted By: Amos
02-Mar-05 - 09:36 AM
Thread Name: BS: What Do Physicists Think About?? IV
Subject: RE: BS: What Do Physicists Think About?? IV
The most distant cluster of galaxies ever found has been revealed by astronomers - and it bears an uncanny resemblance to those nearby. The technique used to discover the cluster promises further discoveries at similar distances, which would help constrain cosmological models.
The cluster of galaxies spotted by astronomers lies 9 billion light-years away. That beats the 8.5 billion light-years' distance of the previous record holder - a jump that represents a "significant fraction of a galaxy's lifespan", says Christopher Mullis, at the University of Michigan in Ann Arbor, US, who led the team.
The universe's first galaxies probably formed a few hundred million years after the big bang. They then began assembling into "proto-clusters", or groups of several hundred, within a billion years. The new-found cluster, which may harbour thousands of galaxies, appears to have started growing when the universe was roughly 2.5 billion years old and stopped about 2 billion years later.
At that time, it had already grown very massive. Only colossal objects can contain the searing, 70-million-degree gas detected by astronomers - the gas is heated as the galaxies fall toward each other. Images from Europe's XMM-Newton spacecraft, launched to study X-rays in 1999, also reveal the gas has taken on a spherical shape - suggesting it has settled into portly middle age.
"We would have thought characters [from so early in the Universe] would have been a bit more youthful," Mullis told New Scientist. "But this guy looks quite old." ...