The COSMOS2015 Catalog: Exploring the 1 < z < 6 Universe with Half a Million Galaxies

Abstract

We present the COSMOS2015 catalog, which contains precise photometric redshifts and stellar masses for more than half a million objects over the 2deg^2 COSMOS field. Including new YJHK_s images from the UltraVISTA-DR2 survey, Y-band images from Subaru/Hyper-Suprime-Cam, and infrared data from the Spitzer Large Area Survey with the Hyper-Suprime-Cam Spitzer legacy program, this near-infrared-selected catalog is highly optimized for the study of galaxy evolution and environments in the early universe. To maximize catalog completeness for bluer objects and at higher redshifts, objects have been detected on a χ^2 sum of the YJHK_s and z^(++) images. The catalog contains ~6 x 10^5 objects in the 1.5 deg^2 UltraVISTA-DR2 region and ~ 1.5 x 10^5 objects are detected in the "ultra-deep stripes" (0.62 deg^2) at K_s ⩽ 24.7 (3σ, 3", AB magnitude). Through a comparison with the zCOSMOS-bright spectroscopic redshifts, we measure a photometric redshift precision of σ_Δz/(1+_s) = 0.007 and a catastrophic failure fraction of η = 0.5%. At 3 < z < 6, using the unique database of spectroscopic redshifts in COSMOS, we find σ_Δz/(1+z_s) = 0.021 and η = 13.2%. The deepest regions reach a 90% completeness limit of 10^10 M_⊙ to z = 4. Detailed comparisons of the color distributions, number counts, and clustering show excellent agreement with the literature in the same mass ranges. COSMOS2015 represents a unique, publicly available, valuable resource with which to investigate the evolution of galaxies within their environment back to the earliest stages of the history of the universe. The COSMOS2015 catalog is distributed via anonymous ftp and through the usual astronomical archive systems (CDS, ESO Phase 3, IRSA).

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