The COSMOS-Legacy survey is a 4.6 Ms Chandra program that has imaged 2.2 deg2 of the COSMOS field with an effective exposure of

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.

We report the spectroscopic confirmation of a sub-mm galaxy (SMG) at z = 4.547 with an estimated L IR = 0.5−2.0×10 13 L ⊙ . The spectra, mid-IR, and X-ray properties indicate the bolometric luminosity is dominated by star formation at a rate of > 1000M ⊙ yr −1 . Multiple, spatially separated components are visible in the Ly-Alpha line with an observed velocity difference of up to 380 km/sec and the object morphology indicates a merger. The best fit spectral energy distribution and spectral line indicators suggest the object is 2-8 Myr old and contains > 10 10 M ⊙ of stellar mass. This object is a likely progenitor for the massive early type systems seen at z ∼ 2.

We have carried out a survey with the Chandra X-Ray Observatory of a sample of 10 bright broad absorption line (BAL) quasars (QSOs). Eight of 10 sources are detected. The six brightest sources have only high-ionization BALs (hiBALs), while the four faintest all show low-ionization BALs (loBALs). We perform a combined spectral Ðt for hiBAL QSOs (384 counts total ; 0.5È6 keV) to determine the mean spectral parameters of this sample. We derive an underlying best-Ðt power-law slope ! \ 1.8^0.35, which is consistent with the mean slope for radio-quiet QSOs from ASCA, but BAL QSOs require a (rest-frame) absorbing column of cm~2, with a partial covering fraction of The 6.5~3 .8 4.5 ] 1022 D80~1 7 9 %. opticalÈtoÈX-ray spectral slope from 2500 to 2 keV) varies from 1.7 to 2.4 across the full sample, (a ox Ó consistent with previous results that BAL QSOs appear to be weak soft X-ray emitters. Removing the absorption component from our best-Ðt spectral model yields a range of from 1.55 to 2.28. All six a ox hiBAL QSOs have deabsorbed X-ray emission consistent with non-BAL QSOs of similar luminosity. The spectral energy distributions of the hiBAL QSOsÈboth the underlying power-law slope and the Ðrst conclusive evidence that BAL QSOs have appeared to be X-ray weak because of a ox Èprovide intrinsic absorption and that their underlying emission is consistent with non-BAL QSOs. By contrast, the removal of the best-Ðt absorption column detected in the hiBAL QSOs still leaves the four loBAL QSOs with values of that are unusually X-ray faint for their optical luminosities, which is consis-a ox [ 2 tent with other evidence that loBALs have higher column density, dustier absorbers. Important questions of whether BAL QSOs represent a special line of sight toward a QSO nucleus or rather an early evolutionary or high-accretion phase in a QSO lifetime remain to be resolved, and the unique properties of loBAL QSOs will be an integral part of that investigation.

We present Chandra X-ray Observatory observations of gigahertz peaked-spectrum (GPS) and compact steep spectrum (CSS) radio sources. The Chandra sample contains 13 quasars and 3 galaxies, with measured 2Y10 keV X-ray luminosities within 10 42 Y10 46 erg s À1 . We detect all of the sources, five of which are observed in X-rays for the first time. We study the X-ray spectral properties of the sample. The measured absorption columns in the quasars are different from those in the galaxies in that the quasars show no absorption (with limits $10 21 cm À2 ), while the galaxies have large absorption columns (>10 22 cm À2 ) consistent with previous findings. The median photon index of the sources with a high signal-to-noise ratio is À ¼ 1:84 AE 0:24, which is larger than the typical index of radio-loud quasars. The arcsec resolution of the Chandra telescope allows us to investigate extended X-ray emission and to look for diffuse components and X-ray jets. We found X-ray jets in two quasars (PKS 1127À145 and B2 0738+32), and an X-ray cluster surrounding a CSS quasar (3C 186; z ¼ 1:1). We detected a possible binary structure in galaxy 0941À080 and an extended diffuse emission in galaxy PKS B1345+125. We discuss our results in the context of X-ray emission processes and radio source evolution. We conclude that the X-ray emission in these sources is most likely unrelated to a relativistic jet, although the sources' radio loudness may suggest a high radiative efficiency for the jet power in these sources.