spacetoday.net: Astronomers detect "dark" galaxies

Posted: Fri, Jul 13, 2012, 7:29 AM ET (1129 GMT)
Dark galaxies spotted by VLT (ESO)

Astronomers announced this week that they have discovered so-called "dark" galaxies from an early phase of the history of the universe. Dark galaxies are small galaxies created in the early universe rich in gas but inefficient in forming stars, and thus emit little light of their own. While dark galaxies had been predicted by models of galaxy formation, they were not observed until astronomers at the European Southern Observatory detected them by looking in the vicinity of bright quasars, whose intense radiation is absorbed by the hydrogen gas in nearby dark galaxies and then emitted as ultraviolet light. That light reaches Earth as violet visible light because of redshifts. Astronomers reported they found 12 such objects in a search using the European Southern Observatory's Very Large Telescope, with an average mass one billion times that the Sun. The discovery, astronomers said, will help support research into the early stages of galaxy formation in the universe.