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|Title:||The Chandra COSMOS Legacy survey: optical/IR identifications||Authors:||MARCHESI, STEFANO
Urry, C. M.
Griffiths, R. E.
LaMassa, S. M.
Silverman, J. D.
|Issue Date:||2016||Journal:||THE ASTROPHYSICAL JOURNAL||Number:||817||Issue:||1||First Page:||34||Abstract:||We present the catalog of optical and infrared counterparts of the Chandra COSMOS-Legacy Survey, a 4.6 Ms Chandra program on the 2.2 deg<SUP>2</SUP> of the COSMOS field, combination of 56 new overlapping observations obtained in Cycle 14 with the previous C-COSMOS survey. In this Paper we report the I, K, and 3.6 μm identifications of the 2273 X-ray point sources detected in the new Cycle 14 observations. We use the likelihood ratio technique to derive the association of optical/infrared (IR) counterparts for 97% of the X-ray sources. We also update the information for the 1743 sources detected in C-COSMOS, using new K and 3.6 μm information not available when the C-COSMOS analysis was performed. The final catalog contains 4016 X-ray sources, 97% of which have an optical/IR counterpart and a photometric redshift, while ≃54% of the sources have a spectroscopic redshift. The full catalog, including spectroscopic and photometric redshifts and optical and X-ray properties described here in detail, is available online. We study several X-ray to optical (X/O) properties: with our large statistics we put better constraints on the X/O flux ratio locus, finding a shift toward faint optical magnitudes in both soft and hard X-ray band. We confirm the existence of a correlation between X/O and the the 2-10 keV luminosity for Type 2 sources. We extend to low luminosities the analysis of the correlation between the fraction of obscured AGNs and the hard band luminosity, finding a different behavior between the optically and X-ray classified obscured fraction.||URI:||http://hdl.handle.net/20.500.12386/26289||URL:||https://iopscience.iop.org/article/10.3847/0004-637X/817/1/34||ISSN:||0004-637X||DOI:||10.3847/0004-637X/817/1/34||Bibcode ADS:||2016ApJ...817...34M||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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