Esther Hu, the lead scientist on the project at the University of Hawaii, says the new finding's distinction isn't very large in universal distance or time, but the incremental finding is rewarding.
"If you want to know something about the conditions under which these objects began to originate it may start to answer, 'when did all galaxies and stars begin to turn on?' It might determine what existed at that time," Hu said.
"At that time" was the "Dark Age" of the universe, a period when swarming clouds of neutral hydrogen and helium first cooled and combined into stars and galaxies. (This could have been anywhere from 15.2 to 12.2 billion years ago, depending on the actual moment the Big Bang occurred, something scientists have not yet agreed on.)
Peering at galaxies from this dawn of light may help reveal how the entire universe evolved, said Hu, whose research required using two scientific slights of hand, together, for the first time.
First, the researchers used the super powerful Keck I and Subaru telescopes at the Mauna Kea Observatory in Hawaii, and narrowed its search with a filter. The filter revealed what are known as Lyman alpha emissions, weak radiation given off by stars and galaxies during their formation. The earliest galaxies have some of the strongest Lyman alpha emissions.
Using the Keck telescope and filter turned out to not be enough. Hu said she and the rest of the team knew they were on the verge of finding an earlier galaxy, but needed even sharper focus.
To magnify the sky further, the astronomers used the galaxy cluster Abell 370 like a magnifying glass. The technique is called gravitational lensing, and it works on Einstein's theory of general relativity. The gravity of an extremely massive object (Abell 370 equal in mass to several hundred galaxies) bends and focuses light.
Looking through Abell 370 magnified the light of the galaxy 4.5 times. The galaxy cluster is like using a lumpy lens and the image of the more distant galaxy is distorted. Yet unraveling the kinks of the image is not the scientists' goal. Observing evidence from the earliest galaxies will solve the mystery of how and why they first formed.
"As we try to look out at larger and larger distances, everything is narrowing down in time," she said. "Now we're getting close to the beginning of galactic formation."
The next big step in finding earlier galaxies will be to use space-based observatories, Hu said.
The Next Generation Space Telescope is scheduled to launch in 2009. Once outside the shroud of our atmosphere, the $500 million telescope is likely to reveal the universe's most ancient galaxies and the secrets they hold.
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