evolution of red galaxies

Much of the debate at the merger conference in Baltimore last week was about the evolution of the red, old, early-type galaxies; what we usually call (stupidly) the red sequence. Today Masjedi, Blanton, and I discussed Masjedi's job applications and dissertation, which all relate to the growth of galaxies on the red sequence. Most studies of the luminosity function of red galaxies suggest an increase of between tens of percent and a factor of two in the total stellar mass on the red sequence since a redshift of unity. As I have mentioned here many times, Masjedi can see this process in action among the SDSS LRGs and can quantitatively limit the mass accretion rate at the most massive end.

Unfortunately, it is at the most massive end that there is the most disagreement about the evolution of red galaxies; Masjedi points out that this can be partially resolved with photometrically selected red galaxies below the spectroscopic limit in the SDSS. He is also working on extending his work on mass accretion to lower-luminosity red galaxies, where the community is in agreement that there has been substantial evolution.