SWIRE/Chandra Lockman Hole Field X-Ray Source Catalog

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_r/f_x > 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_L. The majority of these are red and relatively faint in the optical so that the use of R_L to select those AGNs with the strongest radio emission becomes questionable.

Using the 24-micron to radio flux ratio (q₂₄) 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 q₂₄ is a more reliable indicator of radio-loudness. Use of R_L 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 .