The Extended Chandra Deep Field-South Survey. Chandra Point-Source CatalogsB. D. Lehmer,1W. N. Brandt,1D. M. Alexander,2F. E. Bauer,3D. P. Schneider,1P. Tozzi,4J. Bergeron,5G. P. Garmire,1R. Giacconi,6R. Gilli,7G. Hasinger,8A. E. Hornschemeier,9,6A. M. Koekemoer,10V. Mainieri,8T. Miyaji,11M. Nonino,4P. Rosati,12J. D. Silverman,8G. Szokoly,8& C. Vignali13ABSTRACTWe present Chandra point-source catalogs for the Extended Chandra Deep Field-South(E-CDF-S) survey. The E-CDF-S consists of four contiguous 250 ks Chandra observationscovering an approximately square region of total solid angle ≈0.3 deg2, which flank the exist-ing ≈1 Ms Chandra Deep Field-South (CDF-S). The survey reaches sensitivity limits of ≈1.1× 10−16erg cm−2s−1and ≈6.7 × 10−16erg cm−2s−1for the 0.5–2.0 keV and 2–8 keV bands,respectively. We detect 762 distinct X-ray point sources within the E-CDF-S exposure; 589of these sources are new (i.e., not previously detected in the ≈1 Ms CDF-S). This brings thetotal number of X-ray point sources detected in the E-CDF-S region to 915 (via the E-CDF-Sand ≈1 Ms CDF-S observations). Source positions are determined using matched-filter andcentroiding techniques; the median positional uncertainty is ≈0.0035. The basic X-ray and op-tical properties of these sources indicate a variety of source types, although absorbed activegalactic nuclei (AGNs) seem to dominate. In addition to our main Chandra catalog, we con-structed a supplementary source catalog containing 33 lower significance X-ray point sourcesthat have bright optical counterparts (R < 23). These sources generally have X-ray-to-optical1Department of Astronomy & Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802,USA2Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, United Kingdom3Columbia Astrophysics Laboratory, Columbia University, Pupin Labortories, 550 W. 120th St., Rm 1418, New York, NY10027, USA4INAF - Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34131 Trieste, Italy5Institut d’Astrophysique de Paris, 98bis Boulevard, F-75014 Paris, France6Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA7Istituto Nazionale di Astrofisica (INAF) - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy8Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching b. München, Germany9Laboratory for X-ray Astrophysics, NASA Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA10Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA11Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA12European Southern Observatory, Karl-Schwarzschild-Strasse 2, Garching, D-85748, Germany13Dipartimento di Astronomia, Universitá degli Studi di Bologna, Via Ranzani 1, 40127 Bologna, Italy– 2 –flux ratios expected for normal and starburst galaxies, which lack a strong AGN component.We present basic number-count results for our main Chandra catalog and find good agree-ment with the ≈1 Ms CDF-S for sources with 0.5–2.0 keV and 2–8 keV fluxes greater than3×10−16erg cm−2s−1and 1×10−15erg cm−2s−1, respectively. Furthermore, three extendedsources are detected in the 0.5–2.0 keV band, which are found to be likely associated withgalaxy groups or poor clusters at z ≈ 0.1−0.7; these have typical rest-frame 0.5–2.0 keV lumi-nosities of (1–5) × 1042erg s−1.Subject headings: cosmology: observations — diffuse radiation — galaxies:active — surveys— X-rays1. IntroductionDeep and wide X-ray surveys indicate that the cosmic X-ray background is largely due to accretiononto supermassive black holes (SMBHs) integrated over cosmic time (e.g., see Brandt & Hasinger 2005for a review). Follow-up studies of deep-survey sources with 8–10 m optical telescopes as well as multi-wavelength correlative studies have shown that most of the X-ray sources are active galactic nuclei (AGNs),many of which are obscured (e.g., Bauer et al. 2004; Szokoly et al. 2004; Barger et al. 2005). X-raysurveys have found the highest density of AGNs on the sky (up to ≈7200 deg−2). In addition to AGNs,the deepest X-ray surveys have also detected respectable numbers of starburst and normal galaxies out tocosmologically interesting distances (z ≈ 1; e.g., Hornschemeier et al. 2003; Bauer et al. 2004; Normanet al. 2004).Presently, the two deepest X-ray surveys are the ≈ 2 Ms Chandra Deep Field-North (CDF-N; Brandtetal. 2001, hereafter B01; Alexander et al. 2003, hereafter A03) and the ≈1 Ms Chandra Deep Field-South(CDF-S; Giacconi et al. 2002, hereafter G02). These ≈400 arcmin2surveys have been performed in regionsof sky with extensive multiwavelength coverage. They have provided 50–250 times the sensitivity of surveysby previous X-ray missions, detecting large numbers of point sources (584 for the CDF-N and 346 for theCDF-S; G02; A03) and about a dozen extended groups and poor clusters (Bauer et al. 2002; G02).The X-ray surveys performed to date have explored an impressive amount of the sensitivity ver-sus solid angle “discovery space” (see Figure 1 and Brandt & Hasinger 2005). However, one limita-tion of the present surveys is that there is only a relatively small amount of sky probed to 0.5–2 keVflux levels of (2–50)×10−17erg cm−2s−1, a flux regime where many obscured AGNs are observed (e.g.,Bauer et al. 2004). As a result, our understanding of the X-ray universe at these faint fluxes suffers fromlimited source statistics and field-to-field variance. To mitigate this limitation, the Extended ChandraDeep Field-South (E-CDF-S) survey was undertaken as part of the Chandra Cycle 5 guest observer pro-gram. The E-CDF-S is composed of four 250 ks Chandra ACIS-I pointings flanking the original CDF-S;these are arranged in a contiguous two-by-two pattern and cover a total solid angle of ≈1100 arcmin2.11The ≈1 Ms CDF-S data cover ≈ 35% of the E-CDF-S; much of this coverage, however, has limited sensitivity due to point– 3 –The pointings have sufficient sensitivity to detect the X-ray emission from moderate-luminosity AGNs(LX= 1043–1044erg s−1) to z ≈ 3–6 as well as X-ray luminous starburst galaxies to z ≈ 1. The E-CDF-Stherefore can significantly improve understanding of SMBH accretion at high redshift where the sourcestatistics are still limited. The