  The high ionization-state ions trace the hot gases in the universe, of which
gaseous halos around galaxies are a major contributor. Following Qu & Bregman
(2018), we calculate the gaseous halo contribution to the observed column
density distributions for these ions by convolving the gaseous halo model with
the observed stellar mass function. The predicted column density distribution
reproduces the general shape of the observed column density distribution -- a
broken power law with the break point at $\log N=14.0$ for {\OVI}. Our modeling
suggests that the high column density systems originate from galaxies for which
the virial temperature matches the temperature of the ionization fraction peak.
Specifically, this mass range is $\log M_\star=8.5-10$ for {\OVI}, $\log
M_\star=9.5-10.5$ for {\NeVIII}, and higher for higher ionization state ions
(assuming $T_{\rm max}=2T_{\rm vir}$). A comparison with the observed {\OVI}
column density distribution prefers a large radius model, where the maximum
radius is twice the virial radius. This model may be in conflict with the more
poorly defined {\NeVIII} column density distribution, suggesting further
observations are warranted. The redshift evolution of the high column density
systems is dominated by the change of the cosmic star formation rate, which
decreases from $z=1.0$ to the local universe. Some differences at lower columns
between our models and observations indicate that absorption by the intra-group
(cluster) medium and intergalactic medium are also contributors to the total
column density distributions.
