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THE CHANDRA COSMOS LEGACY SURVEY : OPTICAL/IR IDENTIFICATIONS

Marchesi, S. ; Civano, F. ; Elvis, M. ; Salvato, M. ; Brusa, M. ; Comastri, A. ; Gilli, R. ; Hasinger, G. ; Lanzuisi, G. and Miyaji, T. , et al. (2016) In Astrophysical Journal 817(1).
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 deg2 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... (More)

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 deg2 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.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
catalogs, cosmology: observations, galaxies: active, galaxies: evolution, surveys, X-rays: general
in
Astrophysical Journal
volume
817
issue
1
article number
34
publisher
American Astronomical Society
external identifiers
  • scopus:84955482893
ISSN
0004-637X
DOI
10.3847/0004-637X/817/1/34
language
English
LU publication?
yes
id
4f4b72bb-d294-4a39-9567-9b56077d007e
date added to LUP
2022-10-28 13:49:21
date last changed
2024-04-18 17:44:30
@article{4f4b72bb-d294-4a39-9567-9b56077d007e,
  abstract     = {{<p>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.</p>}},
  author       = {{Marchesi, S. and Civano, F. and Elvis, M. and Salvato, M. and Brusa, M. and Comastri, A. and Gilli, R. and Hasinger, G. and Lanzuisi, G. and Miyaji, T. and Treister, E. and Urry, C. M. and Vignali, C. and Zamorani, G. and Allevato, V. and Cappelluti, N. and Cardamone, C. and Finoguenov, A. and Griffiths, R. E. and Karim, A. and Laigle, C. and Lamassa, S. M. and Jahnke, K. and Ranalli, P. and Schawinski, K. and Schinnerer, E. and Silverman, J. D. and Smolcic, V. and Suh, H. and Trakhtenbrot, B.}},
  issn         = {{0004-637X}},
  keywords     = {{catalogs; cosmology: observations; galaxies: active; galaxies: evolution; surveys; X-rays: general}},
  language     = {{eng}},
  month        = {{01}},
  number       = {{1}},
  publisher    = {{American Astronomical Society}},
  series       = {{Astrophysical Journal}},
  title        = {{THE CHANDRA COSMOS LEGACY SURVEY : OPTICAL/IR IDENTIFICATIONS}},
  url          = {{http://dx.doi.org/10.3847/0004-637X/817/1/34}},
  doi          = {{10.3847/0004-637X/817/1/34}},
  volume       = {{817}},
  year         = {{2016}},
}