MAGIICAT. III. Virial masses

In Churchill et al. (2013ApJ...763L..42C), we used halo abundance matching applied to 182 galaxies in the MgII Absorber-Galaxy Catalog (MAGIICAT) and showed that the mean MgII{lambda}2796 equivalent width follows a tight inverse-square power law, W_r_(2796){prop.to}(D/R_vir_)^-2^, with projected location relative to the galaxy virial radius and that the MgII absorption covering fraction is effectively invariant with galaxy virial mass, M_h_, over the range 10.7<=logM_h_/M_{sun}_<=13.9.

In this work, we explore multivariate relationships between W_r_(2796), virial mass, impact parameter, virial radius, and the theoretical cooling radius that further elucidate self-similarity in the cool/warm (T=10^4^-10^4.5^K) circumgalactic medium (CGM) with virial mass. We show that virial mass determines the extent and strength of the MgII absorbing gas such that the mean W_r_(2796) increases with virial mass at fixed distance while decreasing with galactocentric distance for fixed virial mass.