• DOI:10.3847/0004-637X/817/1/34
• Corpus ID: 55506343

THE CHANDRA COSMOS LEGACY SURVEY: OPTICAL/IR IDENTIFICATIONS

@article{Marchesi2015THECC,
  title={THE CHANDRA COSMOS LEGACY SURVEY: OPTICAL/IR IDENTIFICATIONS},
  author={Stefano Marchesi and Francesca Civano and Martin Elvis and Mara Salvato and Marcella Brusa and Andrea Comastri and Roberto Gilli and Guenther Hasinger and Giorgio Lanzuisi and Takamitsu Miyaji and Ezequiel Treister and C. Meg Urry and Cristian Vignali and Gianni Zamorani and Viola Allevato and Nico Cappelluti and Carie Cardamone and Alexis Finoguenov and Richard E Griffiths and Alexander Karim and Clotilde Laigle and Stephanie M. LaMassa and Knud Jahnke and Piero Ranalli and Kevin Schawinski and Eva Schinnerer and John D. Silverman and Vernesa Smol{\vc}i{\'c} and Hyewon Suh and Benny Trakhtenbrot},
  journal={The Astrophysical Journal},
  year={2015},
  volume={817}
}

• S. Marchesi, F. Civano, +27 authors B. Trakhtenbrot
• Published 3 December 2015
• Physics
• The Astrophysical Journal

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.