Cosmic Baby-boom: Large Population Of Galaxies Found In The Young Universe
- Date:
- September 22, 2005
- Source:
- European Southern Observatory
- Summary:
- The Universe was a more fertile place soon after it was formed than has previously been suspected. This is the conclusion of a team of French and Italian astronomers who, using ESO's Very Large Telescope, made the surprising discovery of a large and unknown population of distant galaxies observed when the Universe was only 10 to 30% its present age. These observations are challenging the current knowledge of the formation and evolution of galaxies.
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The Universe was a more fertile place soon after it wasformed than has previously been suspected. A team of French and Italianastronomers [1] made indeed the surprising discovery of a large andunknown population of distant galaxies observed when the Universe wasonly 10 to 30% its present age.
This breakthrough is based onobservations made with the Visible Multi-Object Spectrograph (VIMOS) aspart of the VIMOS VLT Deep Survey (VVDS). The VVDS started early 2002on Melipal, one of the 8.2-m telescopes of ESO's Very Large TelescopeArray [2].
In a total sample of about 8,000 galaxies selectedonly on the basis of their observed brightness in red light, almost1,000 bright and vigorously star forming galaxies were discovered thatwere formed between 9 and 12 billion years ago (i.e. about 1,500 to4,500 million years after the Big Bang).
"To our surprise, saysOlivier Le Fèvre, from the Laboratoire d'Astrophysique de Marseille(France) and co-leader of the VVDS project, "this is two to six timeshigher than had been found previously. These galaxies had been missedbecause previous surveys had selected objects in a much morerestrictive manner than we did. And they did so to accommodate the muchlower efficiency of the previous generation of instruments."
Whileobservations and models have consistently indicated that the Universehad not yet formed many stars in the first billion years of cosmictime, the discovery announced today by scientists calls for asignificant change in this picture. The astronomers indeed find thatstars formed two to three times faster than previously estimated.
"Theseobservations will demand a profound reassessment of our theories of theformation and evolution of galaxies in a changing Universe", saysGianpaolo Vettolani, the other co-leader of the VVDS project, workingat INAF-IRA in Bologna (Italy).
These results are reported in theSeptember 22 issue of the journal Nature (Le Fèvre et al., "A largepopulation of galaxies 9 to 12 billion years back in the life of theUniverse").
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