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 ($N_{\mathrm{O}\mathrm{V}\mathrm{I}}$) 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 $M^{\ast }={10}^{7.8}$-${10}^{11.2}$ $M_{\odot }$ and galaxy-absorber impact parameters $R_{\perp }=0$-$400$ proper kiloparsecs. In this work, we focus on the variation of $N_{\mathrm{O}\mathrm{V}\mathrm{I}}$ with galaxy mass and impact parameter among the star-forming galaxies in the sample. We find that the average $N_{\mathrm{O}\mathrm{V}\mathrm{I}}$ within one virial radius of a star-forming galaxy is greatest for star-forming galaxies with $M^{\ast }={10}^{9.2}$-${10}^{10}$ $M_{\odot }$. Star-forming galaxies with $M^{\ast }$ 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.