On the possible environmental effect in distributing heavy elements
  beyond individual gaseous halos
  We present a study of extended galaxy halo gas through HI and OVI absorption
over two decades in projected distance at $z\approx0.2$. The study is based on
a sample of $95$ galaxies from a highly complete ($ > 80\%$) survey of faint
galaxies ($L > 0.1L_*$) with archival quasar absorption spectra and $53$
galaxies from the literature. A clear anti-correlation is found between HI
(OVI) column density and virial radius normalized projected distance, $d/R_{\rm
h}$. Strong HI (OVI) absorption systems with column densities greater than
$10^{14.0}$ ($10^{13.5}$) cm$^{-2}$ are found for $48$ of $54$ ($36$ of $42$)
galaxies at $d < \,R_{\rm h}$ indicating a mean covering fraction of
$\langle\kappa_{\rm HI}\rangle=0.89$ ($\langle\kappa_{\rm OVI}\rangle=0.86$).
OVI absorbers are found at $d\approx R_{\rm h}$, beyond the extent observed for
lower ionization species. At $d/R_{\rm h}=1-3$ strong HI (OVI) absorption
systems are found for only $7$ of $43$ ($5$ of $34$) galaxies
($\langle\kappa_{\rm HI}\rangle=0.16$ and $\langle\kappa_{\rm
OVI}\rangle=0.15$). Beyond $d=3\,R_{\rm h}$, the HI and OVI covering fractions
decrease to levels consistent with coincidental systems. The high completeness
of the galaxy survey enables an investigation of environmental dependence of
extended gas properties. Galaxies with nearby neighbors exhibit a modest
increase in OVI covering fraction at $d>R_{\rm h}$ compared to isolated
galaxies ($\kappa_{\rm OVI}\approx0.13$ versus $0.04$) but no excess HI
absorption. These findings suggest that environmental effects play a role in
distributing heavy elements beyond the enriched gaseous halos of individual
galaxies. Finally, we find that differential HI and OVI absorption between
early- and late-type galaxies continues from $d < R_{\rm h}$ to
$d\approx3\,R_{\rm h}$.
