The<i>Chandra</i>Deep Protocluster Survey: point-source catalogues for a 400-ks observation of the<i>z</i>= 3.09 protocluster in SSA22

Abstract

We present X-ray point-source catalogs for a deep 400 ks Chandra ACIS-I\nexposure of the SSA22 field. The observations are centred on a z = 3.09\nprotocluster, which is populated by Lyman break galaxies (LBGs), Lyalpha\nemitters (LAEs), and extended Lyalpha-emitting blobs (LABs). The survey reaches\nultimate (3 count) sensitivity limits of 5.7 X 10^-17 and 3.0 X 10^-16 ergs\ncm^-2 s^-1 for the 0.5-2 keV and 2-8 keV bands, respectively. These limits make\nSSA22 the fourth deepest extragalactic Chandra survey yet conducted, and the\nonly one focused on a known high redshift structure. In total, we detect 297\nX-ray point sources and identify one obvious bright extended X-ray source over\na ~330 arcmin^2 region. In addition to our X-ray catalogs, we provide all\navailable optical spectroscopic redshifts and near-infrared and mid-infrared\nphotometry available for our sources. The basic X-ray and infrared properties\nof our Chandra sources indicate a variety of source types, although absorbed\nactive galactic nuclei (AGNs) appear to dominate. In total, we have identified\n12 X-ray sources (either via optical spectroscopic redshifts or LAE selection)\nat z =3.06-3.12 that are likely to be associated with the SSA22 protocluster.\nThese sources have X-ray and multiwavelength properties that suggest they are\npowered by AGN with 0.5-8 keV luminosities in the range of 10^43-10^45 ergs\ns^-1 We have analysed the AGN fraction of sources in the protocluster as a\nfunction of local LAE source density and find suggestive evidence for a\ncorrelation between AGN fraction and local LAE source density (at the 96 per\ncent confidence level), implying that supermassive black hole growth at z = 3\nis strongest in the highest density regions.\n