Exploring the Mass Segregation Effect of X-ray Sources in Globular Clusters. II. The Case of Terzan 5. (arXiv:1908.06392v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Cheng_Z/0/1/0/all/0/1">Zhongqun Cheng</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_Z/0/1/0/all/0/1">Zhiyuan Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fang_T/0/1/0/all/0/1">Taotao Fang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_X/0/1/0/all/0/1">Xiangdong Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Xu_X/0/1/0/all/0/1">Xiaojie Xu</a>
Using archival {it Chandra} observations with a total effective exposure of
734 ks, we derive an updated catalog of point sources in the massive globular
cluster Terzan 5. Our catalog covers an area of $58.1, rm arcmin^{2}$ ($Rleq
4.3 , rm arcmin$) with 489 X-ray sources, and more than $75%$ of these
sources are first detected in this cluster. We find significant dips in the
radial distribution profiles of X-ray sources in Terzan 5, with the projected
distance and width of the distribution dips for bright ($L_{X} gtrsim
9.5times 10^{30} {rm erg ,s^{-1}}$) X-ray sources are larger than that of
the faint ($L_{X} lesssim 9.5times 10^{30} {rm erg ,s^{-1}}$) sources. By
fitting the radial distribution of the X-ray sources with a”generalized King
model”, we estimated an average mass of $1.48pm0.11,M_{odot}$ and
$1.27pm0.13,M_{odot}$ for the bright and faint X-ray sources, respectively.
These results are in agreement with that observed in 47 Tuc, which may suggest
a universal mass segregation effect for X-ray sources in GCs. Compared with 47
Tuc, we show that the two-body relaxation timescale of Terzan 5 is much
smaller, but its dynamical age is significantly younger than 47 Tuc. These
features suggest that the evolution of Terzan 5 is not purely driven by
two-body relaxation, and tidal stripping effect also plays an important role in
accelerating the dynamical evolution of this cluster.
Using archival {it Chandra} observations with a total effective exposure of
734 ks, we derive an updated catalog of point sources in the massive globular
cluster Terzan 5. Our catalog covers an area of $58.1, rm arcmin^{2}$ ($Rleq
4.3 , rm arcmin$) with 489 X-ray sources, and more than $75%$ of these
sources are first detected in this cluster. We find significant dips in the
radial distribution profiles of X-ray sources in Terzan 5, with the projected
distance and width of the distribution dips for bright ($L_{X} gtrsim
9.5times 10^{30} {rm erg ,s^{-1}}$) X-ray sources are larger than that of
the faint ($L_{X} lesssim 9.5times 10^{30} {rm erg ,s^{-1}}$) sources. By
fitting the radial distribution of the X-ray sources with a”generalized King
model”, we estimated an average mass of $1.48pm0.11,M_{odot}$ and
$1.27pm0.13,M_{odot}$ for the bright and faint X-ray sources, respectively.
These results are in agreement with that observed in 47 Tuc, which may suggest
a universal mass segregation effect for X-ray sources in GCs. Compared with 47
Tuc, we show that the two-body relaxation timescale of Terzan 5 is much
smaller, but its dynamical age is significantly younger than 47 Tuc. These
features suggest that the evolution of Terzan 5 is not purely driven by
two-body relaxation, and tidal stripping effect also plays an important role in
accelerating the dynamical evolution of this cluster.
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