COSMOS PHOTOMETRIC REDSHIFTS WITH 30-BANDS FOR 2-deg2

By O. Ilbert, P. Capak, Mara Salvato, H. Aussel, H. McCracken, D. Sanders, N. Scoville, J. Kartaltepe, Stéphane Arnouts, É. Le Floc'h and 54 more. 2008

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We present accurate photometric redshifts (photo-z) in the 2-deg2 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 χ2 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], Hβ, Hα, and Lyα) 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., Δz = zs − zp) indicates a dispersion of 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 . The deep NIR and Infrared Array Camera coverage enables the photo-z to be extended to z ∼ 2, albeit with a lower accuracy ( at i+AB ∼ 24). The redshift distribution of large magnitude-selected samples is derived and the median redshift is found to range from zm = 0.66 at 22 < i+AB < 22.5 to zm = 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.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/72ab5fed46edc601a76dd17634119b04ee7b44ae

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Citations in the corpus

Accreting supermassive black holes in the COSMOS field and the connection to their host galaxies (2012, background): “…2010); (3) zCOSMOS ID (Lilly et al. 2009) when the object is in the Ne V-selected sample (Mignoli et al., in preparation); (4) photometric ID from Ilbert et al. (2009); (5) RA; (6) Dec.; (7) i-band apparent magnitude; (8) spectroscopic redshift; (9) photometric redshift when the spectroscopy is…”
THE zCOSMOS 10k-BRIGHT SPECTROSCOPIC SAMPLE (2009, methodology): “The fraction with discrepant photo-z can be reduced still further by eliminating objects with bimodal redshift likelihood functions (see Ilbert et al. 2009 for a discussion).”
X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue (2014, methodology): “The computation of photometric redshift by Hsu et al. (in prep) follows the same SED fitting procedures described in Salvato et al. (2011), using SED templates from Ilbert et al. (2009) and Salvato et al. (2009) and software developed for Arnouts et al. (1999) and Ilbert et al. (2006).”
The Horizon-AGN simulation: evolution of galaxy properties over cosmic time (2016, methodology): “It includes the optical datasets from previous releases (Capak et al. 2007; Ilbert et al. 2009), the new Y -band data taken with the Subaru Hyper-Suprime-Cam (PI: Guenther), new nearinfrared (NIR) data from the UltraVISTA-DR2 survey and IR data from the SPLASH program (P. L. Capak et al. in prep.).”
Enhanced star formation rates in AGN hosts with respect to inactive galaxies from PEP-Herschel observations (2012, methodology): “The COSMOS optical catalog is supplemented with K photometry from McCracken et al. (2010), IRAC photometry from Sanders et al. (2007) and Ilbert et al. (2009), and 24µm photometry from Le Floc’h et al. (2009).”
GOODS-Herschel: dust attenuation properties of UV selected high redshift galaxies (2012, background): “These results imply that SED fitting codes must allow for variations of the attenuation curve to fit the UV continuum of galax- ies at all redshifts and retrieve reliable attenuations (Ilbert et al., 2009).”
CLASH: JOINT ANALYSIS OF STRONG-LENSING, WEAK-LENSING SHEAR, AND MAGNIFICATION DATA FOR 20 GALAXY CLUSTERS (2015, methodology): “…statistical agreement was found between the depth estimates 〈β〉 from our BPZ measurements in the cluster fields and those from the COSMOS photometric-redshift catalog (Ilbert et al. 2009), with a median relative offset of 0.27% and an rms field-to- field scatter of 5.0% (Umetsu et al. 2014).”
HerMES: deep number counts at 250 μm, 350 μm and 500 μm in the COSMOS and GOODS-N fields and the build-up of the cosmic infrared background (2012, methodology): “This catalog was matched with photometric redshifts of Ilbert et al. (2009).”
Panchromatic spectral energy distributions of Herschel sources (2013, methodology): “Finally, in COSMOS we adopt the public3 UV-optical catalog, includingU to K broad and intermediate bands (Capak et al. 2007; Ilbert et al. 2009), combined with public spectroscopi (Lilly et al. 2009; Trump et al. 2009) redshifts.”
STELLAR AND TOTAL BARYON MASS FRACTIONS IN GROUPS AND CLUSTERS SINCE REDSHIFT 1 (2009, methodology): “This information is used to estimate the stellar mass of a galaxy, which is obtained from the conversion of the Ks-band luminosity (Ilbert et al. 2009) using an evolving galaxy–type dependent stellar mass-toKs-band luminosity ratio M/LKs (Arnouts et al. 2007).”
Mass assembly in quiescent and star-forming galaxies since z ≃ 4 from UltraVISTA (2013, methodology): “By contrast with Ilbert et al. (2009), we assignthe redshift using the median of the marginalised probability dstribution function rather than the minimumχ2.”
The DEIMOS 10K Spectroscopic Survey Catalog of the COSMOS Field (2018, methodology): “Over 2 million galaxies are detected in deep optical images (Ilbert et al. 2009), and 1.2 million in the NIR (Laigle et al. 2016), spanning 75% of the age of the Universe.”
THE XMM-NEWTON WIDE-FIELD SURVEY IN THE COSMOS FIELD (XMM-COSMOS): DEMOGRAPHY AND MULTIWAVELENGTH PROPERTIES OF OBSCURED AND UNOBSCURED LUMINOUS ACTIVE GALACTIC NUCLEI (2010, background): “…Capak et al. 2007; column 14 and 15); the K-band magnitude (from Mc Cracken et al. 2010; column 16); the magnitudes in the four IRAC channels (from Ilbert et al. 2009; columns 17-20); the MIPS 24µm magnitude (from Le Floc’h et al. 2009; column 21); the spectroscopic redshift (see Section 5;…”
The COSMOS2015 galaxy stellar mass function . Thirteen billion years of stellar mass assembly in ten snapshots (2017, background): “In general, it is considered as an improvement; for example Ilbert et al. (2009), by including templates with emission lines, increase the zphot accuracy by a factor ∼2.5.”
Cosmology from cosmic shear power spectra with Subaru Hyper Suprime-Cam first-year data (2018, methodology): “Therefore, instead of the spec-z sample, we use the 2016 version of the COSMOS 30-band photo-z catalog (Ilbert et al. 2009; Laigle et al. 2016) and accept it as the ground truth.”
PRIMUS: CONSTRAINTS ON STAR FORMATION QUENCHING AND GALAXY MERGING, AND THE EVOLUTION OF THE STELLAR MASS FUNCTION FROM z = 0–1 (2013, methodology): “…M⊙ galaxies in a ∆z = 0.1 wide redshift bin at z = 0.5 due to sample variance in the ∼ 2 deg2 Cosmic Evolution Survey (COSMOS) field, which is among the largest extragalactic deep fields with highquality spectroscopic and medium-band photometric redshifts (Scoville et al. 2007; Ilbert et al. 2009).”
A PUBLIC Ks-SELECTED CATALOG IN THE COSMOS/UltraVISTA FIELD: PHOTOMETRY, PHOTOMETRIC REDSHIFTS, AND STELLAR POPULATION PARAMETERS, (2013, methodology): “This is slightly better than for our Ks-selected catalog; however, Ilbert et al. (2009) use a more restricted set of zspec for this test (∼ 4000 zspec compared to ∼ 5000 zspec in our catalog).”
Cosmological constraints from cosmic shear two-point correlation functions with HSC survey first-year data (2019, methodology): “…that the systematic uncertainties in the redshift distribution of galaxies derived by the re-weighted method bases on the COSMOS 30-band photo-z (Ilbert et al. 2009) might be underestimated and could lead to a bias in the cosmological constraints due to outliers in the COSMOS 30-band catalog.”