Naslov
The Chandra COSMOS Legacy survey: optical/IR identifications

Autori
Marchesi, S. ; Civano, F. ; Elvis, M. ; Salvato, M. ; Brusa, M. ; Comastri, A. ; Gilli, R. ; Hasinger, G. ; Lanzuisi, G. ; Miyaji, T. ; Treister, E. ; Urry, C. M. ; Vignali, C. ; Zamorani, G. ; Allevato, V. ; Cappelluti, N. ; Cardamone, C. ; Finoguenov, A. ; Griffiths, R. E. ; Karim, A. ; Laigle, C. ; LaMassa, S. M. ; Jahnke, K. ; Ranalli, P. ; Schawinski, K. ; Schinnerer, E. ; Silverman, J. D. ; Smolčić, Vernesa ; Suh, H. ; Trakhtenbrot, B.

Izvornik
The Astrophysical journal (0004-637X) 817 (2016), 1; 34-56

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
catalogs ; cosmology: observations ; galaxies: active ; galaxies: evolution ; surveys ; X-rays: general

Sažetak
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.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

POVEZANOST RADA