The
first bright galaxies in the universe apparently formed very rapidly, jumping
from just one or so in number to hundreds in the span of little over 1 percent
of the universe's
age, astronomers find.
Using
either the Hubble Space
Telescope or the Subaru
telescope on Hawaii, one of the world's largest ground telescopes, two
independent teams of astronomers scanned the skies for the faint light emitted
roughly 13 billion years ago by stars in the most distant visible galaxies. The
universe is roughly 13.7 billion years old.
Scientists
can discern the age and distance of a galaxy by looking at how much light from
it has shifted toward the red end of the spectrum. This redshift
measures how the expansion
of the universe since the Big Bang has stretched the wavelengths of light
before it has reached us.
Astronomers
Garth Illingworth and Rychard Bouwens at the University of California at Santa
Cruz discovered 500 or so bright galaxies around 900 million years after the Big Bang.
But just 200 million years earlier, they and a team led by astronomer Masanori
Iye at the National Astronomical Observatory in Tokyo could only confirm the
presence of one such galaxy, with maybe a few more candidates.
"That
suggests evidence for how dramatically things changed," Illingworth told SPACE.com.
"It was a pretty vibrant period in the life of the universe."
Investigating
when and how the first galaxies were formed helps shed light on when stars
first forged the heavier
elements, such as the ones that planets and people are made out of,
Illingworth said.
These
bright galaxies likely built up over time as smaller galaxies not detectable by
current telescopes collided and merged. Getting a better picture of galaxy
formation will have to wait for more advanced telescopes, such as the James
Webb Space Telescope, due to launch in 2013.
"We
are at the very limits of the current technology at probing the most distant
galaxies," Iye said.
Both
teams of scientists reported their findings in the Aug. 14 issue of the journal
Nature.
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