Identification of Faint Chandra X-ray Sources in the Core-Collapsed
  Globular Cluster NGC 6752
  We have searched for optical identifications for 39 Chandra X-ray sources
that lie within the 1.9 arcmin half-mass radius of the nearby (d = 4.0 kpc),
core-collapsed globular cluster, NGC 6752, using deep Hubble Space Telescope
ACS/WFC imaging in B435, R625, and H alpha. Photometry of these images allows
us to classify candidate counterparts based primarily on color-magnitude and
color-color diagram location. The color-color diagram is particularly useful
for quantifying the H alpha line equivalent width. In addition to recovering 11
previously detected optical counterparts, we propose 20 new optical IDs. In
total, there are 16 likely or less certain cataclysmic variables (CVs), nine
likely or less certain chromospherically active binaries, three galaxies, and
three active galactic nuclei (AGNs). The latter three sources, which had been
identified as likely CVs by previous investigations, now appear to be
extragalactic objects based on their proper motions. As we previously found for
NGC 6397, the CV candidates in NGC 6752 fall into a bright group that is
centrally concentrated relative to the turnoff-mass stars and a faint group
that has a spatial distribution that is more similar to that of the
turnoff-mass stars. This is consistent with an evolutionary scenario in which
CVs are produced by dynamical interactions near the cluster center and diffuse
to larger radius orbits as they age.
