The Chandra Cosmos Legacy Survey: Overview and Point Source Catalog

Journal
Date Issued
2016
Author(s)
Civano, F.
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•
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Urry, M. C.
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Elvis, M.
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Cappelluti, N.
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Puccetti, S.
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Brusa, M.
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Zamorani, G.
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Hasinger, G.
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Aldcroft, T.
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Alexander, D. M.
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Brunner, H.
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Capak, P.
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Finoguenov, A.
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Fruscione, A.
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Glotfelty, K.
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Griffiths, R. E.
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Hao, H.
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Harrison, F. A.
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Jahnke, K.
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Kartaltepe, J.
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Karim, A.
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LaMassa, S. M.
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Miyaji, T.
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Ranalli, P.
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Salvato, M.
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Sargent, M.
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Scoville, N. J.
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Schawinski, K.
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Schinnerer, E.
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Silverman, J.
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Smolcic, V.
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Stern, D.
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Toft, S.
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Trakhtenbrot, B.
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Treister, E.
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Vignali, C.
DOI
Abstract
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 ≃ 160 ks over the central 1.5 deg2 and of ≃ 80 ks in the remaining area. The survey is the combination of 56 new observations obtained as an X-ray Visionary Project with the previous C-COSMOS survey. We describe the reduction and analysis of the new observations and the properties of 2273 point sources detected above a spurious probability of 2 × 10-5. We also present the updated properties of the C-COSMOS sources detected in the new data. The whole survey includes 4016 point sources (3814, 2920 and 2440 in the full, soft, and hard band). The limiting depths are 2.2 × 10-16, 1.5 × 10-15, and 8.9 × 10-16 {\text{erg cm}}-2 {{{s}}}-1 in the 0.5-2, 2-10, and 0.5-10 keV bands, respectively. The observed fraction of obscured active galactic nuclei with a column density >1022 cm-2 from the hardness ratio (HR) is ∼50{}-16+17%. Given the large sample we compute source number counts in the hard and soft bands, significantly reducing the uncertainties of 5%-10%. For the first time we compute number counts for obscured (HR > -0.2) and unobscured (HR < -0.2) sources and find significant differences between the two populations in the soft band. Due to the unprecedent large exposure, COSMOS-Legacy area is three times larger than surveys at similar depths and its depth is three times fainter than surveys covering similar areas. The area-flux region occupied by COSMOS-Legacy is likely to remain unsurpassed for years to come.
Volume
819
Issue
1
Start page
62
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2016ApJ...819...62C
Rights
open.access
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