Exploring the Mass Segregation Effect of X-ray Sources in Globular
  Clusters. III. Signs of Binary Disruption in M28
  Using archival {\it Chandra} observations with a total effective exposure of
323 ks, we derive an updated catalog of point sources in the bulge globular
cluster M28. The catalog contains 502 X-ray sources within an area of
$\sim475\, \rm arcmin^{2}$, and more than $90\%$ of these sources are first
detected in this cluster. We find significant dips in the radial distribution
profiles of X-ray sources in M28, with the projected distance and width of the
distribution dip for bright ($L_{X} \gtrsim 4.5\times 10^{30} {\rm\ erg\
\,s^{-1}}$) X-ray sources are larger than the faint ($L_{X} \lesssim 4.5\times
10^{30} {\rm\ erg\ \,s^{-1}}$) sources. The "generalized King model" fitting
give a slightly larger average mass for the bright sources
($1.30\pm0.15\,M_{\odot}$) than the faint sources ($1.09\pm0.14\,M_{\odot}$),
which support a universal mass segregation delay between heavy objects in GCs.
Compared with 47 Tuc and Terzan 5, we show that the dynamical age of M28 is
comparable to Terzan 5 and much smaller than 47 Tuc, but it is evolving more
fast (i.e., with smaller two-body relaxation timescale) than 47 Tuc. These
features may suggest an acceleration effect of cluster dynamical evolution by
tidal shock in M28. Besides, we find an abnormal deficiency of X-ray sources in
the central region ($R \lesssim 1.5 \rm~arcmin$) of M28 than its outskirts,
which indicate that M28 may have suffered an early phase of primordial binary
disruption within its central region, and mass segregation effect will erase
such a phenomenon as cluster evolve to older dynamical age.
