NGC 3115 Chandra X-Ray Point Source Catalog

This table contains some of the results from an in-depth study of low-mass X-ray binaries (LMXBs) detected in the nearby lenticular galaxy NGC 3115 using the Megasecond Chandra X-ray Visionary Project observation (total exposure time 1.1 Ms). In total the authors found 136 candidate LMXBs in the field and 49 in globular clusters (GCs) above 2-sigma detection, with 0.3-8 keV luminosity L&lt;sub&gt;X&lt;/sub&gt; ~ 10&lt;sup&gt;36&lt;/sup&gt; - 10&lt;sup&gt;39&lt;/sup&gt; erg s&lt;sup&gt;-1&lt;/sup&gt;. Other than 13 transient candidates, the sources overall have less long-term variability at higher luminosity, at least at L&lt;sub&gt;X&lt;/sub&gt; &gt;~ 2 x 10&lt;sup&gt;37&lt;/sup&gt; erg s&lt;sup&gt;-1&lt;/sup&gt;. In order to identify the nature and spectral state of these sources, the authors compared their collective spectral properties based on single-component models (a simple power law or a multicolor disk) with the spectral evolution seen in representative Galactic LMXBs. The authors found that in the L&lt;sub&gt;X&lt;/sub&gt; vs. photon index Gamma&lt;sub&gt;PL&lt;/sub&gt; and L&lt;sub&gt;X&lt;/sub&gt; versus disk temperature kT&lt;sub&gt;MCD&lt;/sub&gt; plots, most of their sources fall on a narrow track in which the spectral shape hardens with increasing luminosity below L&lt;sub&gt;X&lt;/sub&gt; ~ 7 x 10&lt;sup&gt;37&lt;/sup&gt; erg s&lt;sup&gt;-1&lt;/sup&gt;, but is relatively constant (Gamma&lt;sub&gt;PL&lt;/sub&gt; ~ 1.5 or kT&lt;sub&gt;MCD&lt;/sub&gt; ~ 1.5 keV) above this luminosity, which is similar to the spectral evolution of Galactic neutron star (NS) LMXBs in the soft state in the Chandra bandpass. Therefore, the authors identified the track as the NS LMXB soft-state track and suggested sources with L&lt;sub&gt;X&lt;/sub&gt; &lt;~ 10&lt;sup&gt;37&lt;/sup&gt; erg s&lt;sup&gt;-1&lt;/sup&gt; as atolls in the soft state and those with L&lt;sub&gt;X&lt;/sub&gt; &gt;~ 10&lt;sup&gt;37&lt;/sup&gt; erg s&lt;sup&gt;-1&lt;/sup&gt; as Z sources. Ten other sources (five are transients) displayed significantly softer spectra and are probably black hole X-ray binaries in the thermal state. One of them (a persistent source) is in a metal-poor GC. The 11 Chandra observations of NGC 3115 are listed in Table 1 of the reference paper. They were made during three epochs: one in 2001,two in 2010, and nine in 2012. All observations used the imaging array of the AXAF CCD Imaging Spectrometer (ACIS). This table contains the properties of the 482 detected point sources in the merged and single Chandra ACIS observations of NGC 3115 above a 2-sigma threshold and after eliminating a number of spurious sources associated with bright streaks on the ACIS-S1 chip and (in one case) on a CCD edge. 469 of these sources (indicated by values of obs_flag = &#39;0&#39;) have a single entry in this table, based on their properties as derived from all of the available Chandra data for that position. There are 13 transient sources (having obs_flag = &#39;h&#39;) for which an additional entry is provided referring to their properties in the &quot;high state&quot;, and based on the combination of their high-state observations, as shown in Figures 3(a) - 3(d) in the reference paper. For source number 198, there is a second additional entry provided referring to its properties in the &quot;low state&quot;, and based on the combination of its low-state observations, as shown in Figure 3(c) in the reference paper. Thus, there are 496 entries (rows) in this table, i.e., 482 + 13 + 1. This table was created by the HEASARC in August 2015 based on the union of the machine-readable versions of Table 3 (the master source catalog) and Table 4 (the source counts, fluxes and hardness ratios in the merged observations) that were obtained from the ApJ web site. It does not contain the source counts and fluxes in the individual observations which were given in Table 5 of the reference paper. This is a service provided by NASA HEASARC .

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Organization: National Aeronautics and Space Administration