SWIRE/Chandra Lockman Hole Field X-Ray Source Catalog

The authors have carried out a moderate-depth (70 ks), contiguous 0.7 square degrees Chandra survey in the Lockman Hole Field of the Spitzer/SWIRE Legacy Survey coincident with a completed, ultra-deep VLA survey with deep optical and near-infrared imaging in-hand. The primary motivation is to distinguish starburst galaxies and active galactic nuclei (AGNs), including the significant, highly obscured (log N<sub>H</sub> > 23 cm<sup>-2</sup>) subset. Chandra has detected 775 X-ray sources to a limiting broadband (0.3 - 8 keV) flux of ~4 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup>. This table contains the X-ray catalog, fluxes, hardness ratios, and multi-wavelength fluxes. The log N versus log S agrees with those of previous surveys covering similar flux ranges. The Chandra and Spitzer flux limits are well matched: 771 (99%) of the X-ray sources have infrared (IR) or optical counterparts, and 333 have MIPS 24-micron detections. There are four optical-only X-ray sources and four with no visible optical/IR counterpart. The very deep (~2.7 microJansky rms) VLA data yield 251 (> 4 sigma) radio counterparts, 44% of the X-ray sources in the field. The authors confirm that the tendency for lower X-ray flux sources to be harder is primarily due to absorption. As expected, there is no correlation between observed IR and X-ray fluxes. Optically bright, type 1, and red AGNs lie in distinct regions of the IR versus X-ray flux plots, demonstrating the wide range of spectral energy distributions in this sample and providing the potential for classification/source selection. Many optically bright sources, which lie outside the AGN region in the optical versus X-ray plots (f<sub>r</sub>/f<sub>x</sub> > 10), lie inside the region predicted for red AGNs in IR versus X-ray plots, consistent with the presence of an active nucleus. More than 40% of the X-ray sources in the VLA field are radio-loud using the classical definition of R<sub>L</sub>. The majority of these are red and relatively faint in the optical so that the use of R<sub>L</sub> to select those AGNs with the strongest radio emission becomes questionable. Using the 24-micron to radio flux ratio (q<sub>24</sub>) instead results in 13 of the 147 AGNs with sufficient data being classified as radio-loud, in good agreement with the ~10% expected for broad-lined AGNs based on optical surveys. The authors conclude that q<sub>24</sub> is a more reliable indicator of radio-loudness. Use of R<sub>L</sub> should be confined to the optically selected type 1 AGN. This table was created by the HEASARC in December 2009 based on the machine-readable versions of Tables 3, 4 and 7 from the reference paper which was obtained from the Astrophysical Journal web site. This is a service provided by NASA HEASARC .

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  "Astrophysics"
]