On the connection between the metal-enriched intergalactic medium and galaxies: an OVI-galaxy cross-correlation study at $z < 1$
We present new results on the auto- and cross-correlation functions of galaxies and OVI absorbers in a $\sim 18~\textrm{Gpc}^3$ comoving volume at $z < 1$. We use a sample of 51,296 galaxies and 140 OVI absorbers in the column density range $13 \lesssim \log N \lesssim 15$ to measure two-point correlation functions in the two dimensions transverse and orthogonal to the line-of-sight $ξ(r_{\perp}, r_{\parallel})$. We furthermore infer the corresponding 'real-space' correlation functions, $ξ(r)$, by projecting $ξ(r_{\perp}, r_{\parallel})$ along $r_{\parallel}$, and assuming a power-law form, $ξ(r) = (r / r_0)^{-γ}$. Comparing the results from the absorber-galaxy cross-correlation function, $ξ_{\textrm{ag}}$, the galaxy auto-correlation function, $ξ_{\textrm{gg}}$, and the absorber auto-correlation function, $ξ_{\textrm{aa}}$, we constrain the statistical connection between galaxies and the metal-enriched intergalactic medium as a function of star-formation activity. We also compare these results to predictions from the EAGLE cosmological hydrodynamical simulation and find a reasonable agreement. We find that: (i) OVI absorbers show very little velocity dispersion with respect to galaxies on $\sim$ Mpc scales, likely $\lesssim$ 100 \kms; (ii) OVI absorbers and galaxies may not linearly trace the same underlying distribution of matter in general. In particular, our results demonstrate that OVI absorbers are less clustered, and potentially more extended around galaxies than galaxies are around themselves; (iii) On $\gtrsim 100$ kpc scales, the likelihood of finding OVI absorbers around star-forming galaxies is similar to the likelihood of finding OVI absorbers around non star-forming galaxies (abridged)