THE SELF-SIMILARITY OF THE CIRCUMGALACTIC MEDIUM WITH GALAXY VIRIAL MASS: IMPLICATIONS FOR COLD-MODE ACCRETION

We apply halo abundance matching to obtain galaxy virial masses, M-h, and radii, R-vir, for 183 isolated galaxies from the Mg II Absorber-Galaxy Catalog. All galaxies have spectroscopic redshifts (0.07 <= z <= 1.12) and their circumgalactic medium (CGM) is probed in Mg II absorption within projected galactocentric distances D <= 200 kpc. We examine the behavior of equivalent width, W-r (2796), and covering fraction, f(c), as a function of D, D/R-vir, and M-h. Bifurcating the sample at the median mass log M-h/M-circle dot = 12, we find (1) systematic segregation of M-h on the W-r (2796)-D plane (4.0 sigma); high-mass halos are found at higher D with larger W-r (2796) compared to low-mass halos. On the W-r (2796)-D/R-vir plane, mass segregation vanishes and we find W-r (2796) proportional to (D/R-vir)(-2) (8.9 sigma). (2) High-mass halos have larger f(c) at a given D, whereas f(c) is independent of M-h at all D/R-vir. (3) f(c) is constant with M-h over the range 10.7 <= log M-h/M-circle dot <= 13.9 within a given D or D/R-vir. The combined results suggest the Mg II absorbing CGM is self-similar with halo mass, even above log M-h/M-circle dot similar or equal to 12, where cold mode accretion is predicted to be quenched. If theory is correct, either outflows or sub-halos must contribute to absorption in high-mass halos such that low- and high-mass halos are observationally indistinguishable using Mg II absorption strength once impact parameter is scaled by halo mass. Alternatively, the data may indicate predictions of a universal shut down of cold-mode accretion in high-mass halos may require revision.