The farther away you look, the farther back in time you see. So, GN-108036, a galaxy spotted by NASA’s Spitzer and Hubble scopes, is 12.9 billion light-years away, and thus, about 12.9 billion years ago (not counting adjustments for cosmic expansion). It turns out that GN-108036 is producing stars at the rate of about 100 per year. In contract, the Mikly Way (our galaxy), even though it is 100 times bigger in mass than GN-108036, produces about 30 new stars per year.
GN-108036 is an unexpected find because we previously thought that a that early stage in the universe’s history, about 750 million years after the Big Bang, galaxies this massive and bright did not exist yet.
From the NASA press release:
Astronomers were surprised to see such a large burst of star formation because the galaxy is so small and from such an early cosmic era. Back when galaxies were first forming, in the first few hundreds of millions of years after the Big Bang, they were much smaller than they are today, having yet to bulk up in mass.
During this epoch, as the universe expanded and cooled after its explosive start, hydrogen atoms permeating the cosmos formed a thick fog that was opaque to ultraviolet light. This period, before the first stars and galaxies had formed and illuminated the universe, is referred to as the “dark ages.” The era came to an end when light from the earliest galaxies burned through, or “ionized,” the opaque gas, causing it to become transparent. Galaxies similar to GN-108036 may have played an important role in this event.
“The high rate of star formation found for GN-108036 implies that it was rapidly building up its mass some 750 million years after the Big Bang, when the universe was only about five percent of its present age,” said Bahram Mobasher, a team member from the University of California, Riverside. “This was therefore a likely ancestor of massive and evolved galaxies seen today.”