Akari North Ecliptic Pole Deep Field Chandra X-Ray Point Source Catalog

This table contains results from the 300-ks Chandra survey in the AKARI North Ecliptic Pole (NEP) deep field. This field has a unique set of 9-band infrared photometry covering 2-24 micron from the AKARI Infrared Camera, including mid-infrared (MIR) bands not covered by Spitzer. The survey is one of the deepest ever achieved at ~15 micron, and is by far the widest among those with similar depths in the MIR. This makes this field unique for the MIR-selection of AGN at z ~1. The authors have designed a source detection procedure, which performs joint Maximum Likelihood PSF fits on all of their 15 mosaicked Chandra pointings covering an area of 0.34 square degrees. The procedure has been highly optimized and tested by simulations. A point source catalog with photometry and Bayesian-based 90%-confidence upper limits in the 0.5-7, 0.5-2, 2-7, 2-4, and 4-7 keV bands has been produced. The catalog contains 457 X-ray sources and the spurious fraction is estimated to be ~1.7%. Sensitivity and 90%-confidence upper flux limits maps in all bands are provided as well. In their study, the authors searched for optical MIR counterparts in the central 0.25 square degrees, where deep Subaru Suprime-Cam multi-band images exist. Among the 377 X-ray sources detected therein, ~80% have optical counterparts and ~60% also have AKARI mid-IR counterparts. The authors cross-matched their X-ray sources with MIR-selected AGN from Hanami et al. (2012, PASJ, 64, 70). Around 30% of all AGN that have MID-IR SEDs purely explainable by AGN activity are strong Compton-thick AGN candidates. The source catalog contained in this table uses an internal threshold of ML = 9.5 which corresponds to ML&lt;sub&gt;empir&lt;/sub&gt; ~12 (see Sect. 4.3.3 of the reference paper for more details). In total, 457 sources are detected, of which 377 objects fall in the deep Subaru imaging region (shown in Figure 1 of the reference paper). This catalog is designed to identify X-ray emitting objects in the Chandra/AKARI NEP deep field. Together with the optimized cross-identification procedure, the clear advantage of the catalog is the very high reliability, while the catalog sacrifices completeness for objects with low counts (see Figure 9 in the paper). Only ~1.7% of the objects listed in the source catalog are expected to be spurious source detections. The two sources that have an ML-threshold in the 0.5-7 keV band below 9.5 originate from a 0.5-7 keV single-band source detection run. To quote similar ML values for all objects, the authors list the total 0.5-7 keV ML values from the joint 3-energy band source detection run. The listed counts, count rates, fluxes, and the corresponding uncertainties in the 0.5-7 keV band are taken from the single-band detection run. Considering the uncertainty in the astrometric calibration, all sources should be considered as possible X-ray counterparts that are within a radius of r&lt;sub&gt;match&lt;/sub&gt; = sqrt(sigma&lt;sub&gt;total&lt;/sub&gt;&lt;sup&gt;2&lt;/sup&gt;+sigma&lt;sub&gt;astro&lt;/sub&gt;&lt;sup&gt;2&lt;/sup&gt;), with sigma&lt;sub&gt;total&lt;/sub&gt; = 5 * sqrt(sigma&lt;sub&gt;sys&lt;/sub&gt;&lt;sup&gt;2&lt;/sup&gt;+sigma&lt;sub&gt;stat&lt;/sub&gt;&lt;sup&gt;2&lt;/sup&gt;) and sigma&lt;sub&gt;sys&lt;/sub&gt; = 0.1 arcseconds and sigma&lt;sub&gt;astro&lt;/sub&gt; = 0.2 arcseconds (astrometric uncertainty). The authors also created a low-probability source catalog (not contained in this present HEASARC table): they caution that, due to the significant number of spurious sources in the low-probability catalog, it should NOT be used to select X-ray sources or to increase the sample size of X-ray-selected objects. It can be of interest if the scientific goal requires one to EXCLUDE potential X-ray emitting objects from a sample with a high completeness, since, using this strategy, one accepts those objects that are excluded are not associated with an X-ray-emitting object. The low-probability source catalog (available at &lt;a href="http://cdsarc.u-strasbg.fr/ftp/cats/J_MNRAS/446/911/"&gt;http://cdsarc.u-strasbg.fr/ftp/cats/J_MNRAS/446/911/&lt;/a&gt; as the files lowpscat.dat.gz and lowpscat.fits) has a lower maximum likelihood threshold than the main source catalog (an internal threshold of ML = 5, corresponding to ML&lt;sub&gt;empir&lt;/sub&gt; ~9.5). This catalog contains 626 detected sources, of which 506 are located within the deep Subaru imaging region. Based on their simulated data, the authors conclude that 19% of all the low-probability source catalog entries are false detections. Considering only the deep Subaru imaging area the spurious source fraction drops to 15%. When using information from this catalog, please cite the reference paper: Krumpe et al. (2015, MNRAS, 446, 911). This table was created by the HEASARC in August 2015 based on CDS table J/MNRAS/446/911 files mainscat.dat, the main source catalog. Some of the values for the name parameter in the HEASARC&#39;s implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .

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Organization: National Aeronautics and Space Administration