Posted on 07/10/2007 2:52:26 PM PDT by NormsRevenge
Astronomers have found evidence for the most distant galaxies ever detected.
The galaxies are seen as they existed just 500 million years after the birth of the universe. Their light, traversing the cosmos for more than 13 billion years, was seen only because it was distorted in a natural "gravitational lens" created by the gravity-bending mass of a nearer cluster of galaxies.
"Gravitational lensing is the magnification of distant sources by foreground structures," explained Caltech astronomer Richard Ellis, who led the international team. "By looking through carefully selected clusters, we have located six star-forming galaxies seen at unprecedented distances, corresponding to a time when the universe was only 500 million years old, or less than 4 percent of its present age."
The universe is estimated to be 13.7 billion years old, so that puts the newfound galaxies at 13.2 billion light-years away. A light-year is the distance light travels in a year, about 6 trillion miles (10 trillion kilometers).
Tricky technique
The team found the galaxies using the 10-meter Keck II telescope atop Mauna Kea on the Big Island of Hawaii. The finding will be presented tomorrow at a conference of the Geological Society in London.
The light from the half-dozen faraway star-forming galaxies was boosted about 20 times by the magnifying effect of the foreground galaxy cluster, said team member Dan Stark, a Caltech graduate student.
Gravitational lensing is tricky, the researchers admit. To bolster their case, they point to very ancient galaxies that are just slightly closer, yet which already contain old stars.
"To produce these old stars requires significant earlier activity, most likely in the fainter star-forming galaxies we have now seen," Stark said.
End of the Dark Ages
The galaxies offer a glimpse of an era shortly after the first stars formed.
After the theoretical Big Bang, there were no stars. Eventually, a thick "fog" was effectively burned off by hot, young stars, ending what's called the cosmic Dark Ages.
"That we should find so many distant galaxies in our small survey area suggests they are very numerous indeed," Stark said. "We estimate the combined radiation output of this population could be sufficient to break apart (ionize) the hydrogen atoms in space at that time, thereby ending the Dark Ages."
“Space got bigger.”
Whew, I’m glad it didn’t only happen to me then. :)
So does that mean that matter that "rides" on space is not subject to the speed of light and thus has traveled faster than the speed of light to get that distance from our galaxy? And that universal expansion exceeds light speed? And how long until that matter slows down to "under" light speed?
Doesn't this explanation imply that there is a possibility these galaxies are now as much as 26 billion light years away and we are seeing the light from where they were 13 billion years ago?
“So does that mean that matter that “rides” on space is not subject to the speed of light and thus has traveled faster than the speed of light to get that distance from our galaxy”
Maybe I should said “sits” on space rather than “rides” on space. A galaxy outside our local group that is not gravitationally bound to us sits on a piece of space that is moving away from us because of universal expansion.
Space is expanding between us. Neither of us is moving at faster than light speed, but the distance between us could grow, I suppose, at a rate faster than light travels if the distance increase is because of expansion. The individual galaxy is bound internally and possibly locally by gravitational forces keeping its constituents together.
I'm guessing English 101 isn't what it used to be...
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.