Cross-correlation redshift calibration without spectroscopic calibration samples in DES science verification data

Davis, C, Rozo, E, Roodman, A, Alarcon, A, Cawthon, R, Gatti, M, Lin, H, Miquel, R, Rykoff, E S, Troxel, M A, Vielzeuf, P, Romer, A K and and, the DES Collaboration (2018) Cross-correlation redshift calibration without spectroscopic calibration samples in DES science verification data. Monthly Notices of the Royal Astronomical Society, 477 (2). pp. 2196-2208. ISSN 0035-8711

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Galaxy cross-correlations with high-fidelity redshift samples hold the potential to precisely calibrate systematic photometric redshift uncertainties arising from the unavailability of complete and representative training and validation samples of galaxies. However, application of this technique in the Dark Energy Survey (DES) is hampered by the relatively low number density, small area, and modest redshift overlap between photometric and spectroscopic samples. We propose instead using photometric catalogues with reliable photometric redshifts for photo-z calibration via cross-correlations. We verify the viability of our proposal using redMaPPer clusters from the Sloan Digital Sky Survey (SDSS) to successfully recover the redshift distribution of SDSS spectroscopic galaxies. We demonstrate how to combine photo-z with cross-correlation data to calibrate photometric redshift biases while marginalizing over possible clustering bias evolution in either the calibration or unknown photometric samples. We apply our method to DES Science Verification (DES SV) data in order to constrain the photometric redshift distribution of a galaxy sample selected for weak lensing studies, constraining the mean of the tomographic redshift distributions to a statistical uncertainty of z ∼ ±0.01. We forecast that our proposal can, in principle, control photometric redshift

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QB Astronomy
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Depositing User: Billy Wichaidit
Date Deposited: 15 May 2018 14:35
Last Modified: 15 May 2018 14:35

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Project NameSussex Project NumberFunderFunder Ref
University of Sussex Astronomy Consolidated Grant 2017-2020G2050STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCILST/P000525/1