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dc.contributor.authorHong, JaeSub
dc.contributor.authorvan den Berg, Maureen
dc.contributor.authorGrindlay, Jonathan E.
dc.contributor.authorLaycock, Silas
dc.date.accessioned2019-09-25T14:11:52Z
dc.date.issued2009
dc.identifier.citationHong, JaeSub, Maureen van den Berg, Jonathan E. Grindlay, and Silas Laycock. 2009. “RADIAL DISTRIBUTION OF X-RAY POINT SOURCES NEAR THE GALACTIC CENTER.” The Astrophysical Journal 706 (1): 223–37. https://doi.org/10.1088/0004-637x/706/1/223.
dc.identifier.issn0004-637X
dc.identifier.issn1538-4357
dc.identifier.urihttp://nrs.harvard.edu/urn-3:HUL.InstRepos:41399744*
dc.description.abstractWe present the log N-log S and spatial distributions of X-ray point sources in seven Galactic bulge (GB) fields within 4 degrees from the Galactic center (GC). We compare the properties of 1159 X-ray point sources discovered in our deep (100 ks) Chandra observations of three low extinction Window fields near the GC with the X-ray sources in the other GB fields centered around Sgr B2, Sgr C, the Arches Cluster, and Sgr A* using Chandra archival data. To reduce the systematic errors induced by the uncertain X-ray spectra of the sources coupled with field-and-distance-dependent extinction, we classify the X-ray sources using quantile analysis and estimate their fluxes accordingly. The result indicates that the GB X-ray population is highly concentrated at the center, more heavily than the stellar distribution models. It extends out to more than 1 degrees.4 from the GC, and the projected density follows an empirical radial relation inversely proportional to the offset from the GC. We also compare the total X-ray and infrared surface brightness using the Chandra and Spitzer observations of the regions. The radial distribution of the total infrared surface brightness from the 3.6 band mu m images appears to resemble the radial distribution of the X-ray point sources better than that predicted by the stellar distribution models. Assuming a simple power-law model for the X-ray spectra, the closer to the GC the intrinsically harder the X-ray spectra appear, but adding an iron emission line at 6.7 keV in the model allows the spectra of the GB X-ray sources to be largely consistent across the region. This implies that the majority of these GB X-ray sources can be of the same or similar type. Their X-ray luminosity and spectral properties support the idea that the most likely candidate is magnetic cataclysmic variables (CVs), primarily intermediate polars (IPs). Their observed number density is also consistent with the majority being IPs, provided the relative CV to star density in the GB is not smaller than the value in the local solar neighborhood.
dc.language.isoen_US
dc.publisherAmerican Astronomical Society
dash.licenseLAA
dc.titleRadial Distribution of X-ray Point Sources Near the Galactic Center
dc.typeJournal Article
dc.description.versionVersion of Record
dc.relation.journalThe Astrophysical Journal
dash.depositing.authorGrindlay, Jonathan E.::60a4e0fa703c94a1ad5c71189cf4844e::600
dc.date.available2019-09-25T14:11:52Z
dash.workflow.comments1Science Serial ID 98246
dc.identifier.doi10.1088/0004-637X/706/1/223
dash.source.volume706;1
dash.source.page223-237


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