Quiescent galaxies from SHELS and SDSS

For redshift z<0.6, we derive mass-limited samples and demonstrate that these large samples enhance constraints on the evolution of the quiescent population. The constraints include 2985 new velocity dispersions from the SHELS F2 survey.

In contrast with the known substantial evolution of size with redshift, evolution in the velocity dispersion is negligible. The dynamical-to-stellar-mass ratio increases significantly as the universe ages, in agreement with recent results that combine high-redshift data with the Sloan Digital Sky Survey. Like other investigators, we interpret this result as an indication that the dark matter fraction within the effective radius increases as a result of the impact of the minor mergers that are responsible for size growth.