Mauna Kea astronomers glimpse light that's billions of years old
Six distant galaxies date back to when the universe was young
WAIMEA, Hawaii » Using a natural magnifying glass the size of many galaxies, astronomers on Mauna Kea have seen traces of extraordinarily more distant galaxies in existence when the universe was just 500 million years old.
The universe is thought to be 13.7 billion years old, so light from the most distant of these galaxies has been approaching us for about 13.2 billion years.
The discovery of six such distant galaxies was announced today at a meeting of the Geological Society in London by Richard Ellis of the California Institute of Technology, leader of the team which found them, using the Keck II telescope on Mauna Kea.
The previous most distant object, also seen with the "gravitational lens" of foreground galaxies, existed when the universe was 800 million years old.
Astronomers calculate the distance of an object by its red shift, the degree to which its light is stretched and made infrared by the expansion of the universe.
The previous most distant object had a stretching index or red shift of 7. The new ones have red shifts from 8.7 to 10.2.
"Wow!" said Richard Crowe, a Hilo astronomer with the Imiloa Astronomy Education Center and the University of Hawaii at Hilo. "That's an amazing piece of information."
It's amazing because not too much earlier than that, no light could head towards Earth. That was the "Dark Ages," a time when the universe was much smaller, filled with thick, opaque hydrogen gas that soaked up light as soon as it was produced, said Keck Observatory spokeswoman Laura Kinoshita.
At some point the universe expanded enough, and the electrical nature of the hydrogen changed enough, that light began to shine; exactly when isn't clear.
Since the Keck team's observations are 300 million years closer to the Big Bang than the previous most distance object, the discoveries may indicate that the early universe developed more rapidly than thought, Crowe said.
These discoveries were possible because a cluster of other galaxies, closer to us, got in the way. Rather than block the distant light, the gravity of the closer galaxies pulled scattered light beams back on track for a rendezvous with Earth.
The foreground cluster boosted the amount of light from the distant galaxies about 20-fold, said Caltech graduate student Dan Stark, who began the study which made the discoveries.
"That we should find so many distant galaxies in our small survey area suggests they are very numerous indeed," Stark said.
And the fact that there are so many indicates they are the source of energy which made the electrical changes in early hydrogen atoms and ended the dark period, he said.