Post by glactus on Feb 13, 2010 5:35:24 GMT
The Plateau de Bure millimeter interferometer (Iram) in the southern French Alps.
Stars form from giant gas clouds in galaxies - the starfomation rate, however, has changed over cosmic timescales. In the young Universe many more stars were born.
.Scientists from the Max Planck Institute for Extraterrestrial Physics, together with an international team of astronomers have found a plausible explanation: a few billion years after the Big Bang, normal star-forming galaxies contained five to ten times more cold gas than today, providing more "food" to fuel the star-formation process.
"We have been able, for the first time, to detect and image the cold molecular gas in normal star-forming galaxies which are representative of the typical massive galaxy populations shortly after the Big Bang," said Linda Tacconi from the Max Planck Institute for Extraterrestrial Physics, who is the lead author of a paper in this week's issue of Nature.
The challenging observations yield the first glimpse how galaxies, or more precisely the cold gas in these galaxies, looked a mere 3 to 5 billion years after the Big Bang (equivalent to a cosmological redshift z ~ 2 to z ~ 1). At this epoch, galaxies seem to have formed stars more or less continuously with at least ten times the rate seen in similar-mass systems in the local Universe.
Over the past decade astronomers have established a global framework of how galaxies formed and evolved when the Universe was only a few billion years old. Gas cooled and collected in concentrations of the mysterious 'dark' matter (so-called dark-matter halos).
Over cosmological timescales, gas accreting from these halos onto the proto-galaxies, and collisions and mergers of galaxies, subsequently led to the hierarchical build-up of galaxy mass.
"A major study of distant, luminous star-forming galaxies at the Plateau de Bure millimeter interferometer has now resulted in a break-through by having a direct look at the star-formation "food".
Credits: Max Planck Institute for Extraterrestrial Physics.
This is part text only. See full text and all scientists nvolved at Space daily.com
www.spacedaily.com/reports/Young_Galaxies_Gorge_On_Gas_999.html