November 1, 2013
Astronomers Find Earliest Galaxy Ever
[ Watch the Video: Lucky Find For Astronomers - Most Distant, Earliest Galaxy Yet ]
Brett Smith for redOrbit.com - Your Universe Online
Using data from the recently conducted survey of the early universe performed by NASA’s Hubble Space Telescope, an international team led by American astronomers has identified the most distant and earliest galaxy ever detected, according to a recently published report in the journal Nature.
Although many other more distant candidates for the earliest galaxy have been identified in the past, this galaxy was confirmed via follow-up observations from the Keck I telescope in Hawaii.
The researchers said their finding indicates the infant universe held a greater number of intense star-forming galaxies than astronomers previously believed. This would mean that theories and models of galaxies’ star formation activity may need revision.
“We expected to find a lot more small objects with this survey,” said Mauro Giavalisco, study author and University of Massachusetts Amherst astronomer.
The UMass astronomer compared the prevailing theory about the early universe to throwing a brick through a window, which would produce many small pieces and a few large shards.
According to Giavalisco, theory predicts there should be “many small-mass galaxies but just a few large ones. And our survey was not really designed to find these early galaxies with such a high rate of star formation. However, on the first try we see this very active object. So we’re not sure if we’re really, really lucky or if our predictive models are slightly off."
Evidence of the rate of star formation in this galaxy raises “a tantalizing question about whether we’ve got the theory of galaxy formation correct in its fundamental ideas,” the astronomer added. “Predictions about the star formation rate distribution of galaxies are related to the physics of gas accretion onto galaxies and subsequent gas expulsion from them,” Giavalisco said. “These mechanisms are not yet fully understood.”
To confirm the nature of this distant galaxy, the team used used a technique called the “Lyman-break selection,” which was developed by Giavalisco and colleagues in the 1990s. The method uses the apparent colors of galaxies as a crude distance indicator.
“Colors encode a lot of physical processes at work in them,” Giavalisco said, “such as whether they form stars or not and how much dust is in them, because dust dims stellar light and makes their colors redder.”