The Chandra Deep Field–South Survey: 2 Ms Source Catalogs

Abstract

We present point-source catalogs for the {\~{}}2 Ms exposure of the Chandra Deep Field-South (CDF-S) this is one of the two most sensitive X-ray surveys ever performed. The survey covers an area of {\~{}}436 arcmin2 and reaches on-axis sensitivity limits of {\~{}}1.9×10-17 and {\~{}}1.3×10-16 ergs cm-2 s-1 for the 0.5-2.0 and 2-8 keV bands, respectively. Four hundred and sixty-two X-ray point sources are detected in at least one of three X-ray bands that were searched; 135 of these sources are new compared to the previous {\~{}}1 Ms CDF-S detections. Source positions are determined using centroid and matched-filter techniques; the median positional uncertainty is {\~{}}0.36". The X-ray-to-optical flux ratios of the newly detected sources indicate a variety of source types; {\~{}}55{\%} of them appear to be active galactic nuclei, while {\~{}}45{\%} appear to be starburst and normal galaxies. In addition to the main Chandra catalog, we provide a supplementary catalog of 86 X-ray sources in the {\~{}}2 Ms CDF-S footprint that was created by merging the {\~{}}250 ks Extended Chandra Deep Field-South with the CDF-S this approach provides additional sensitivity in the outer portions of the CDF-S. A second supplementary catalog that contains 30 X-ray sources was constructed by matching lower significance X-ray sources to bright optical counterparts (R{\textless}23.8) the majority of these sources appear to be starburst and normal galaxies. The total number of sources in the main and supplementary catalogs is 578. Optical R-band counterparts and basic optical and infrared photometry are provided for the X-ray sources in the main and supplementary catalogs. We also include existing spectroscopic redshifts for 224 of the X-ray sources. The average backgrounds in the 0.5-2.0 and 2-8 keV bands are 0.066 and 0.167 counts Ms-1 pixel-1, respectively, and the background counts follow Poisson distributions. The effective exposure times and sensitivity limits of the CDF-S are now comparable to those of the {\~{}}2 Ms Chandra Deep Field-North (CDF-N). We also present cumulative number counts for the main catalog and compare the results to those for the CDF-N. The soft-band number counts for these two fields agree well with each other at fluxes higher than {\~{}}2×10-16 ergs cm-2 s-1, while the CDF-S number counts are up to {\~{}}25{\%} smaller than those for the CDF-N at fluxes below {\~{}}2×10-16 ergs cm-2 s-1 in the soft band and {\~{}}2×10-15 ergs cm-2 s-1 in the hard band, suggesting small field-to-field variations.