The CGM$^2$ Survey: Circumgalactic O VI from dwarf to massive
  star-forming galaxies
  We combine 126 new galaxy-O VI absorber pairs from the CGM$^2$ survey with
123 pairs drawn from the literature to examine the simultaneous dependence of
the column density of O VI absorbers ($N_{\rm O VI}$) on galaxy stellar mass,
star formation rate, and impact parameter. The combined sample consists of 249
galaxy-O VI absorber pairs covering $z=0$-$0.6$, with host galaxy stellar
masses $M^*=10^{7.8}$-$10^{11.2}$ $M_\odot$ and galaxy-absorber impact
parameters $R_\perp=0$-$400$ proper kiloparsecs. In this work, we focus on the
variation of $N_{\rm O VI}$ with galaxy mass and impact parameter among the
star-forming galaxies in the sample. We find that the average $N_{\rm O VI}$
within one virial radius of a star-forming galaxy is greatest for star-forming
galaxies with $M^*=10^{9.2}$-$10^{10}$ $M_\odot$. Star-forming galaxies with
$M^*$ between $10^{8}$ and $10^{11.2}$ $M_\odot$ can explain most O VI systems
with column densities greater than 10$^{13.5}$ cm$^{-2}$. 60% of the O VI mass
associated with a star-forming galaxy is found within one virial radius and 35%
is found between one and two virial radii. In general, we find that some
departure from hydrostatic equilibrium in the CGM is necessary to reproduce the
observed O VI amount, galaxy mass dependence, and extent. Our measurements
serve as a test set for CGM models over a broad range of host galaxy masses.
