Redshift distributions of galaxies in the Dark Energy Survey Science Verification shear catalogue and implications for weak lensing

C. Bonnett , M. A. Troxel , W. Hartley , A. Amara , B. Leistedt , M. R. Becker , G. M. Bernstein , S. L. Bridle , C. Bruderer , M. T. Busha , M. Carrasco Kind , M. J. Childress , F. J. Castander , C. Chang , M. Crocce , T. M. Davis , T. F. Eifler , J. Frieman , C. Gangkofner , E. Gaztanaga , K. Glazebrook , D. Gruen , T. Kacprzak , A. King , J. Kwan , O. Lahav , G. Lewis , C. Lidman , H. Lin , N. Maccrann , R. Miquel , C. R. O'Neill , A. Palmese , H. V. Peiris , A. Refregier , E. Rozo , E. S. Rykoff , I. Sadeh , C. Sánchez , E. Sheldon , S. Uddin , R. H. Wechsler , J. Zuntz , T. Abbott , F. B. Abdalla , S. Allam , R. Armstrong , M. Banerji , A. H. Bauer , A. Benoit-Lévy , E. Bertin (1) , D. Brooks , E. Buckley-Geer , D. L. Burke , D. Capozzi , A. Carnero Rosell , J. Carretero , C. E. Cunha , C. B. d'Andrea , L. N. da Costa , D. L. Depoy , S. Desai , H. T. Diehl , J. P. Dietrich , P. Doel , A. Fausti Neto , E. Fernandez , B. Flaugher , P. Fosalba , D. W. Gerdes , R. A. Gruendl , K. Honscheid , B. Jain , D. J. James , M. Jarvis , A. G. Kim , K. Kuehn , N. Kuropatkin , T. S. Li , M. Lima , M. A. G. Maia , M. March , J. L. Marshall , P. Martini , P. Melchior , C. J. Miller , E. Neilsen , R. C. Nichol , B. Nord , R. Ogando , A. A. Plazas , K. Reil , A. K. Romer , A. Roodman , M. Sako , E. Sanchez , B. Santiago , R. C. Smith , M. Soares-Santos , F. Sobreira , E. Suchyta , M. E. C. Swanson , G. Tarle , J. Thaler , D. Thomas , V. Vikram , A. R. Walker

1 IAP - Institut d'Astrophysique de Paris

We present photometric redshift estimates for galaxies used in the weak lensing analysis of the Dark Energy Survey Science Verification (DES SV) data. Four model- or machine learning-based photometric redshift methods—annz2, bpz calibrated against BCC-Ufig simulations, skynet, and tpz—are analyzed. For training, calibration, and testing of these methods, we construct a catalogue of spectroscopically confirmed galaxies matched against DES SV data. The performance of the methods is evaluated against the matched spectroscopic catalogue, focusing on metrics relevant for weak lensing analyses, with additional validation against COSMOS photo-z 's. From the galaxies in the DES SV shear catalogue, which have mean redshift 0.72 ±0.01 over the range 0.3 8 of approximately 3%. This shift is within the one sigma statistical errors on σ₈ for the DES SV shear catalogue. We further study the potential impact of systematic differences on the critical surface density, Σ_crit , finding levels of bias safely less than the statistical power of DES SV data. We recommend a final Gaussian prior for the photo-z bias in the mean of n (z ) of width 0.05 for each of the three tomographic bins, and show that this is a sufficient bias model for the corresponding cosmology analysis.

Mots clés: Astrophysics - Cosmology and Nongalactic Astrophysics

Domaines: Planète et Univers [physics]

C. Bonnett, M. A. Troxel, W. Hartley, A. Amara, B. Leistedt, et al.. Redshift distributions of galaxies in the Dark Energy Survey Science Verification shear catalogue and implications for weak lensing. Physical Review D, 2016, 94, ⟨10.1103/PhysRevD.94.042005⟩. ⟨hal-03645093⟩