Pristine gas from nascent universe
THE cold gas is flowing, they said, into a galaxy that is now seen as it looked about 11 billion years ago, due to the time its light takes to get here.
Profuse gas flows like this are thought to be key to explaining that early era, when galaxies were copiously forming stars from the gas. A similar flow could have contributed to the creation of our own galaxy.
The astronomers – led by Neil Crighton of Swinburne University in the U.K. – published the findings Oct. 2 in the research journal Astrophysical Journal Letters.
The distant hydrogen usually can't be detected. But in this case it was, thanks to a coincidental lighting arrangement provided by a distant, extremely bright object known as a quasar, according to Crighton's group.
The findings came from a systematic survey using the Large Binocular Telescope on Mount Graham, Arizona and an instrument called a spectrograph on the Keck I telescope on the summit of Mauna Kea, Hawaii.
Cosmologists believe early galaxies received their material from a vast reservoir of pristine hydrogen floating between galaxies. About 10 billion years ago when the universe was one-fifth its current age, studies have found, fledgling galaxies were forming new stars at nearly 100 times their current rate. This activity would require some fuel in the form of gas, since that is what makes up stars.
In the past decade, supercomputer simulations of galaxy formation have predicted that this gas funnels into galaxies along thin "cold streams" which, like streams of snow melt feeding a mountain lake, channel cool gas from the surrounding area onto galaxies.
Testing these predictions isn't easy, as such gas at the edges of galaxies is very dark. Instead, the team of astronomers searched for places where quasars could provide helpful light. Quasars are galaxies that briefly shine as the brightest objects in the universe as their central object, a black hole, sucks up material in a violent process.
Source: World Science