X-Ray Spectroscopy of Newly Identified ULXs Associated With M87’s Globular Cluster Population. (arXiv:2007.00671v1 [astro-ph.HE])

X-Ray Spectroscopy of Newly Identified ULXs Associated With M87’s Globular Cluster Population. (arXiv:2007.00671v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Dage_K/0/1/0/all/0/1">Kristen C. Dage</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zepf_S/0/1/0/all/0/1">Stephen E. Zepf</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Thygesen_E/0/1/0/all/0/1">Erica Thygesen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bahramian_A/0/1/0/all/0/1">Arash Bahramian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kundu_A/0/1/0/all/0/1">Arunav Kundu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maccarone_T/0/1/0/all/0/1">Thomas J. Maccarone</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Peacock_M/0/1/0/all/0/1">Mark B. Peacock</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Strader_J/0/1/0/all/0/1">Jay Strader</a>

We have identified seven ultraluminous X-ray sources (ULXs) which are
coincident with globular cluster candidates (GCs) associated with M87. ULXs in
the old GC environment represent a new population of ULXs, and ones likely to
be black holes. In this study we perform detailed X-ray spectroscopic followup
to seven GC ULXs across a wealth of archival Chandra observations and long time
baseline of 16 years. This study brings the total known sample of GC ULXs to
17. Two of these sources show variability in their X-ray luminosity of an order
of magnitude over many years, and one of these sources shows
intra-observational variability on the scale of hours. While the X-ray spectra
of the majority of globular cluster ULXs are best fit by single component
models, one of the sources studied in this paper is the second GC ULX to be
best fit by a two component model. We compare this new sample of GC ULXs to the
previously studied sample, and compare the X-ray and optical properties
counterparts across the samples. We find that the clusters that host ULXs in
M87 have metallicities from g-z=1.01 to g-z=1.70. The best-fit power-law
indices of the X-ray spectra range from Gamma=1.37-2.21, and the best fit inner
black-body disk temperatures range from kT=0.56-1.90 keV.

We have identified seven ultraluminous X-ray sources (ULXs) which are
coincident with globular cluster candidates (GCs) associated with M87. ULXs in
the old GC environment represent a new population of ULXs, and ones likely to
be black holes. In this study we perform detailed X-ray spectroscopic followup
to seven GC ULXs across a wealth of archival Chandra observations and long time
baseline of 16 years. This study brings the total known sample of GC ULXs to
17. Two of these sources show variability in their X-ray luminosity of an order
of magnitude over many years, and one of these sources shows
intra-observational variability on the scale of hours. While the X-ray spectra
of the majority of globular cluster ULXs are best fit by single component
models, one of the sources studied in this paper is the second GC ULX to be
best fit by a two component model. We compare this new sample of GC ULXs to the
previously studied sample, and compare the X-ray and optical properties
counterparts across the samples. We find that the clusters that host ULXs in
M87 have metallicities from g-z=1.01 to g-z=1.70. The best-fit power-law
indices of the X-ray spectra range from Gamma=1.37-2.21, and the best fit inner
black-body disk temperatures range from kT=0.56-1.90 keV.

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