Evolution of CIV Absorbers. II. Where does CIV live?
  We use the observed cumulative statistics of CIV absorbers and dark matter
halos to infer the distribution of CIV-absorbing gas relative to galaxies at
redshifts $0\!\leq\!z\!\leq\!5$. We compare the cosmic incidence $dN/dX$ of CIV
absorber populations and galaxy halos, finding that massive $L \geq L_{\star}$
halos alone cannot account for all the observed $W_r \geq 0.05$~{\AA}
absorbers. However, the $dN/dX$ of lower mass halos exceeds that of $W_r \geq
0.05$~{\AA} absorbers. We also estimate the characteristic gas radius of
absorbing structures required for the observed CIV $dN/dX$, assuming each
absorber is associated with a single galaxy halo. The $W_r \geq 0.3$~{\AA} and
$W_r \geq 0.6$~{\AA} CIV gas radii are $\sim30-70\%$ ($\sim20-40\%$) of the
virial radius of $L_{\star}$ ($0.1L_{\star}$) galaxies, and the $W_r \geq
0.05$~{\AA} gas radius is $\sim100-150\%$($\sim60-100\%$) of the virial radius
of $L_{\star}$ ($0.1L_{\star}$) galaxies. For stronger absorbers, the gas
radius relative to virial radius rises across Cosmic Noon and falls afterwards,
while for weaker absorbers, the relative gas radius declines across Cosmic Noon
and then dramatically rises at $z\!<\!1$. A strong luminosity-dependence of gas
radius implies highly extended CIV envelopes around massive galaxies before
Cosmic Noon, while a luminosity-independent gas radius implies highly extended
envelopes around dwarf galaxies after Cosmic Noon. From available
absorber-galaxy and CIV evolution data, we favor a scenario in which low-mass
galaxies enrich the volume around massive galaxies at early epochs and propose
that the outer halo gas ($>0.5R_v$) was produced primarily in ancient satellite
dwarf galaxy outflows, while the inner halo gas ($<0.5R_v$) originated from the
central galaxy and persists as recycled accreting gas.
