The Satellite Population Around Luminous Red Galaxies in the Legacy Surveys

Abstract

Luminous Red Galaxies, or LRGs, were originally selected in the Sloan Digital Sky Survey as good tracers of large scale structure. Subsequent investigations showed them to be among the most massive galaxies in the Universe and dominated by uniformly old stellar populations. Despite being dominated by old stars, however, they have grown in stellar mass since z=1, implying that they grow predominantly via accretion of mostly passive satellites. This picture has not yet been tested because of the lack of deep imaging data sets that both covers a large enough area of the sky to contain substantial numbers of LRGs and also is deep enough to detect faint satellites. I will present our initial characterization the satellite galaxy population of LRGs out to z=0.65. To accomplish this I use the Legacy Surveys, which are comprised of grz imaging to 2-2.5 mag deeper than SDSS, over a larger footprint, and with better image quality. Specifically, I will present our first measurement of the number of satellite galaxies around LRGs and how this number depends on LRG properties.