THE CHANDRA COSMOS SURVEY. I. OVERVIEW AND POINT SOURCE CATALOG

Abstract

The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra program that has imaged the central 0.5 sq.deg of the COSMOS field (centered at 10 h , +02 o ) with an effective exposure of ∼160 ksec, and an outer 0.4 sq.deg. area with an effective exposure of ∼80 ksec. The limiting source detection depths are 1.9×10 −16 erg cm −2 s −1 in the Soft (0.5-2 keV) band, 7.3×10 −16 erg cm −2 s −1 in the Hard (2-10 keV) band, and 5.7×10 −16 erg cm −2 s −1 in the Full (0.5-10 keV) band. Here we describe the strategy, design and execution of the C-COSMOS survey, and present the catalog of 1761 point sources detected at a probability of being spurious of <2×10 −5 (1655 in the Full, 1340 in the Soft, and 1017 in the Hard bands). By using a grid of 36 heavily (∼50%) overlapping pointing positions with the ACIS-I imager, a remarkably uniform (±12%) exposure across the inner 0.5 sq.deg field was obtained, leading to a sharply defined lower flux limit. The widely different PSFs obtained in each exposure at each point in the field required a novel source detection method, because of the overlapping tiling strategy, which is described in a companion paper. This method produced reliable sources down to a 7-12 counts, as verified by the resulting logN-logS curve, with sub-arcsecond positions, enabling optical and infrared identifications of virtually all sources, as reported in a second companion paper. The full catalog is described here in detail and is available on-line.

CF-HiZELS, an ∼10 deg2 emission-line survey with spectroscopic follow-up: Hα, [O iii] + Hβ and [O ii] luminosity functions at z = 0.8, 1.4 and 2.2

“…We start by using C-COSMOS (Elvis et al 2009) to find that, in agreement with Garn et al (2010), only ∼1 per cent of Hα sources are detected in the X-rays (five sources, X-ray luminosities of 10 42.8 ± 0.11 erg s −1 ). We also use deep IRAC data, in both COSMOS and UDS, to look for sources dominated by signatures of the stellar bump (starforming dominated), thus showing a blue colour beyond ∼1.6 μm rest frame and sources dominated by signatures of a red power law (AGN-dominated), showing red colours even beyond ∼1.6 μm rest frame (see e.g.…”

The evolution of the X-ray luminosity functions of unabsorbed and absorbed AGNs out to z∼ 5

“…In each of the remaining fields we adopt data from a single Chandra survey: the 2Ms survey in CDFN (Alexander et al 2003); the ∼160ks C-COSMOS observations (Elvis et al 2009;Puccetti et al 2009); and the 5ks XBootes survey (Murray et al 2005).…”

The dark matter haloes of moderate luminosity X-ray AGN as determined from weak gravitational lensing and host stellar masses

“…The AGN sample used for this work is selected by combining the COSMOS XMM-Newton (XMM-COSMOS; Cappelluti et al 2009) and Chandra (C-COSMOS; Elvis et al 2009) X-ray catalogues. The XMM-COSMOS survey covers 2 deg 2 to a limiting depth of 5 × 10 −16 erg cm −2 s −1 in the soft (0.5-2 keV) band and 3 × 10 −15 erg cm −2 s −1 in the hard (2-10 keV) band.…”