COSMOS PHOTOMETRIC REDSHIFTS WITH 30-BANDS FOR 2-deg²

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Abstract

We present accurate photometric redshifts (photo-z) in the 2-deg 2 COSMOS field. The redshifts are computed with 30 broad, intermediate, and narrowbands covering the UV (Galaxy Evolution Explorer), visible near-IR (NIR; Subaru, Canada-France-Hawaii Telescope (CFHT), United Kingdom Infrared Telescope, and National Optical Astronomy Observatory), and mid-IR (Spitzer/IRAC). A 2 template-fitting method (Le Phare) was used and calibrated with large spectroscopic samples from the Very Large Telescope Visible Multi-Object Spectrograph and the Keck Deep Extragalactic Imaging Multi-Object Spectrograph. We develop and implement a new method which accounts for the contributions from emission lines ([O ii], H, H, and Ly) to the spectral energy distributions (SEDs). The treatment of emission lines improves the photo-z accuracy by a factor of 2.5. Comparison of the derived photo-z with 4148 spectroscopic redshifts (i.e., z = z sz p ) indicates a dispersion of z/(1+z s ) = 0.007 at i + AB < 22.5, a factor of 2-6 times more accurate than earlier photo-z in the COSMOS, CFHT Legacy Survey, and the Classifying Object by Medium-Band Observations-17 survey fields. At fainter magnitudes i + AB < 24 and z < 1.25, the accuracy is z/(1+z s ) = 0.012. The deep NIR and Infrared Array Camera coverage enables the photo-z to be extended to z 2, albeit with a lower accuracy ( z/(1+z s ) = 0.06 at i + AB 24). The redshift distribution of large magnitude-selected samples is derived and the median redshift is found to range from z m = 0.66 at 22 < i + AB < 22.5 to z m = 1.06 at 24.5 < i + AB < 25. At i + AB < 26.0, the multiwavelength COSMOS catalog includes approximately 607,617 objects. The COSMOS-30 photo-z enables the full exploitation of this survey for studies of galaxy and large-scale structure evolution at high redshift.

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The record

Venue

The Astrophysical Journal

Topic

Astronomy and Astrophysical Research

Field

Physics and Astronomy

Canadian institutions

—

Funders

National Astronomical Observatory of JapanCentre National de la Recherche ScientifiqueAspen Center for PhysicsCalifornia Institute of TechnologyNational Aeronautics and Space AdministrationJet Propulsion LaboratoryEuropean Southern ObservatorySpace Telescope Science InstituteNational Science Foundation

Keywords

RedshiftSpectrographTelescopeSpectral energy distributionPhotometric redshiftEmission spectrumInfraredVery Large TelescopeGalaxy

Has abstract in OpenAlex

yes

API

/api/v1/works/W2167952501