Physical Conditions of Five O VI Absorption Systems Towards PG
  $1522+101$
  We present the analysis of five O VI absorbers identified across a redshift
path of z $\sim (0.6 - 1.3)$ towards the background quasar PG $1522+101$ with
information on five consecutive ionization stages of oxygen from O II to O VI.
The combined $HST$ and $Keck$ spectra cover UV, redshifted EUV, and optical
transitions from a multitude of ions spanning ionization energies in the range
of $\sim (13 - 300)$ eV. Low ionization (C II, O II, Si II, Mg II) and very
high ionization species (Ne VIII, Mg X) are non-detections in all the
absorbers. Three of the absorbers have coverage of He I, in one of which it is
a $> 3 \sigma$ detection. The kinematic structures of these absorbers are
extracted from C IV detected in $HIRES$ spectra. The farthest absorber in our
sample also contains the detections of Ne V and Ne VI. Assuming co-spatial
absorbing components, the ionization models show the medium to be multiphased
with small-scale density-temperature inhomogeneities that are sometimes
kinematically unresolved. In two of the absorbers, there is an explicit
indication of the presence of a warm gas phase ($T \gtrsim 10^5$ K) traced by O
VI. In the remaining absorbers, the column densities of the ions are consistent
with a non-uniform photoionized medium. The sub-solar [C/O] relative abundances
inferred for the absorbers point at enrichment from massive Type II supernovae.
Despite metal enrichment, the inferred wide range for [O/H] $\sim$ [$-2.1,
+0.2$] amongst the absorbers along with their anti-correlation with the
observed H I suggest poor small-scale mixing of metals with hydrogen in the
regions surrounding galaxies and the IGM.
