BY DR EMILY BALDWIN
Posted: 23 April, 2009
Galaxies have been observed undergoing furious bursts of star formation during a very early period of the Universe, long before established models of galaxy formation predict that they should. This revelation came at the European Week of Astronomy and Space Science in a presentation by Dr Kristen Coppin of Durham University.
Coppin led a team of astronomers from Durham and the Max Planck Institute, together known as the LESS collaboration, who used the Large Apex Bolometer Camera on the Atacama Pathfinder Experiment (APEX) at the European Southern Observatory. The collaboration surveyed distant galaxies observed in the so-called Extended Chandra Deep Field South, but at sub-millimetre wavelengths rather than the X-ray wavelengths of Chandra.
These galaxies, which reach back to just a billion years after the big bang (a redshift greater than four), turn out to be very dusty. Dust is a by-product of stars, and it is possible to estimate the star-formation rate by the amount of dust present. According to Coppin, the hundred or so galaxies observed were churning out several thousand new stars per year. In comparison, our Milky Way is currently only making on average ten new stars per year.
These sub-millimetre galaxies are the pre-cursors of the giant elliptical galaxies, and Coppin says that mergers with smaller galaxies may be powering the starbursts. However, the conventional picture is that this process of merging galaxies to build up larger ones took much longer to finish, yet in spite of this these observed sub-millimetre galaxies are almost complete. These latest observations add more fuel to the fire that massive galaxy formation happened much quicker than we realised, which may have implications for models of the cold dark matter haloes that were the birthing grounds for the first galaxies.