The extreme synchronicity of stellar ages of red galaxies in [...] (S. Andreon et al.)
- Published on 07 April 2011
In section 1. Letters
The extreme synchronicity of stellar ages of red galaxies in the JKCS041 cluster at z=2.2
How fast did galaxies form? How fast did they form their stars? In the galaxy cluster JKCS041 at z=2.2 (one quarter of the age of the universe), red massive galaxies show a tight distribution in color, whose small scatter indicates a star formation history that is highly synchronized across galaxies. This can be interpreted as a spread in stellar age of 160+/-30 Myr, as if all stars in these galaxies were formed in a single event. This would not be expected in the hierachical scenario, where massive galaxies are progressively formed through merging episodes sometimes involving gas, hence star formation.