A $Chandra-Swift$ View of Point Sources in Hickson Compact Groups: High
  AGN fraction but a dearth of strong AGNs
  We present $Chandra$ X-ray point source catalogs for 9 Hickson Compact Groups
(HCGs, 37 galaxies) at distances $34 - 89$ Mpc. We perform detailed X-ray point
source detection and photometry, and interpret the point source population by
means of simulated hardness ratios. We thus estimate X-ray luminosities ($L_X$)
for all sources, most of which are too weak for reliable spectral fitting. For
all sources, we provide catalogs with counts, count rates, power-law indices
($\Gamma$), hardness ratios, and $L_X$, in the full ($0.5-8.0$ keV), soft
($0.5-2.0$ keV) and hard ($2.0-8.0$ keV) bands. We use optical emission-line
ratios from the literature to re-classify 24 galaxies as star-forming,
accreting onto a supermassive black hole (AGNs), transition objects, or
low-ionization nuclear emission regions (LINERs). Two-thirds of our galaxies
have nuclear X-ray sources with $Swift$/UVOT counterparts. Two nuclei have
$L_{X,{\rm 0.5-8.0 keV}}$~$ > 10^{42}$ erg s$^{-1}$, are strong
multi-wavelength AGNs and follow the known $\alpha_{\rm OX}-\nu L_{\nu,\rm near
UV}$ correlation for strong AGNs. Otherwise, most nuclei are X-ray faint,
consistent with either a low-luminosity AGN or a nuclear X-ray binary
population, and fall in the "non-AGN locus" in $\alpha_{\rm OX}-\nu L_{\nu,\rm
near UV}$ space, which also hosts other, normal, galaxies. Our results suggest
that HCG X-ray nuclei in high specific star formation rate spiral galaxies are
likely dominated by star formation, while those with low specific star
formation rates in earlier types likely harbor a weak AGN. The AGN fraction in
HCG galaxies with $M_R \le -20$ and $L_{X,{\rm 0.5-8.0 keV}} \ge 10^{41}$ erg
s$^{-1}$ is $0.08^{+0.35}_{-0.01}$, somewhat higher than the $\sim 5%$ fraction
in galaxy clusters.
