COSMOS Photometric Redshifts with 30-bands for 2-deg2

O. Ilbert (1, 2, 3) , P. Capak (4) , M. Salvato (5) , H. Aussel (6) , H. J. Mccracken (7) , D. B. Sanders (6) , N. Scoville (4) , J. Kartaltepe (6) , S. Arnouts (3) , E. Le Floc'H (8) , B. Mobasher (9) , Y. Taniguchi (6) , F. Lamareille (8, 10, 11) , A. Leauthaud (3) , S. Sasaki (12) , D. Thompson (13, 14, 15) , M. Zamojski (6) , G. Zamorani (16, 17) , S. Bardelli (16, 18) , M. Bolzonella (19) , A. Bongiorno (19) , M. Brusa (6) , K. I. Caputi (6) , C. M. Carollo (20) , T. Contini (10, 11) , R. Cook (6) , G. Coppa (6) , O. Cucciati (17, 21) , S. de La Torre (6) , L. de Ravel (6) , P. Franzetti (16, 18) , B. Garilli (16, 18) , G. Hasinger (6) , A. Iovino (16, 18) , P. Kampczyk (6) , J. -P. Kneib (3, 10, 22) , C. Knobel (6) , K. Kovac (6) , J. F. Le Borgne (11, 22) , V. Le Brun (3) , O. Le Fevre (3) , S. Lilly (6) , D. Looper (6) , C. Maier (6) , V. Mainieri (6) , Y. Mellier (7, 23, 24) , M. Mignoli (6) , T. Murayama (6) , R. Pello (10, 11, 22) , Y. Peng (25) , E. Perez-Montero (6) , A. Renzini (6) , E. Ricciardelli (6) , David Schiminovich (4) , M. Scodeggio (16, 18) , Y. Shioya (6) , J. Silverman (6) , J. Surace (6) , M. Tanaka (26, 27, 28) , L. Tasca (3) , L. Tresse (3) , D. Vergani (29) , E. Zucca (16, 17)

1 Institut d'Astrophysique et de Géophysique [Liège]
2 OAB - INAF - Osservatorio Astronomico di Bologna
3 LAM - Laboratoire d'Astrophysique de Marseille
4 CALTECH - California Institute of Technology
5 MPIA - Max-Planck-Institut für Astronomie
6 AUTRES
7 IAP - Institut d'Astrophysique de Paris
8 OP - Observatoire de Paris - Site de Paris
9 STSci - Space Telescope Science Institute
10 LATT - Laboratoire Astrophysique de Toulouse-Tarbes
11 LATT - Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées
12 LPS - Laboratoire de Physique Statistique de l'ENS
13 School of Biological Sciences
14 NIWA - National Institute of Water and Atmospheric Research [Christchurch]
15 NIWA - National Institute of Water and Atmospheric Research [Wellington]
16 OAC - INAF - Osservatorio Astronomico di Capodimonte
17 OAB - INAF - Osservatorio Astronomico di Brera
18 OABO - INAF - Osservatorio Astronomico di Bologna
19 UNIBO - Alma Mater Studiorum Università di Bologna = University of Bologna
20 University of Chicago
21 Dipartimento di Fisica
22 UMS 831 - Services communs OMP
23 DEMIRM - Departement de Radioastronomie Millimétrique
24 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
25 Institute of Astronomy [ETH Zürich]
26 Information Science Laboratory
27 Tokai University
28 Japan Atomic Energy Agency
29 OAA - INAF - Osservatorio Astrofisico di Arcetri

We present accurate photometric redshifts in the 2-deg2 COSMOS field. The redshifts are computed with 30 broad, intermediate, and narrow bands covering the UV (GALEX), Visible-NIR (Subaru, CFHT, UKIRT and NOAO) and mid-IR (Spitzer/IRAC). A chi2 template-fitting method (Le Phare) was used and calibrated with large spectroscopic samples from VLT-VIMOS and Keck-DEIMOS. We develop and implement a new method which accounts for the contributions from emission lines (OII, Hbeta, Halpha 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. Delta z = zs - zp) indicates a dispersion of sigma_{Delta z/(1+zs)}=0.007 at i<22.5, a factor of 2-6 times more accurate than earlier photo-z in the COSMOS, CFHTLS and COMBO-17 survey fields. At fainter magnitudes i<24 and z<1.25, the accuracy is sigma_{Delta z/(1+zs)}=0.012. The deep NIR and IRAC coverage enables the photo-z to be extended to z~2 albeit with a lower accuracy (sigma_{Delta z/(1+zs)}=0.06 at i~24). The redshift distribution of large magnitude-selected samples is derived and the median redshift is found to range from z=0.66 at 22

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]

O. Ilbert, P. Capak, M. Salvato, H. Aussel, H. J. Mccracken, et al.. COSMOS Photometric Redshifts with 30-bands for 2-deg2. 2008. ⟨hal-00325551⟩