Davis, C;
Rozo, E;
Roodman, A;
Alarcon, A;
Cawthon, R;
Gatti, M;
Lin, H;
... DES Collaboration, .; + view all
(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.
10.1093/mnras/sty787.
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Abstract
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 Δz ~ ±0.01. We forecast that our proposal can, in principle, control photometric redshift uncertainties in DES weak lensing experiments at a level near the intrinsic statistical noise of the experiment over the range of redshifts where redMaPPer clusters are available. Our results provide strong motivation to launch a programme to fully characterize the systematic errors from bias evolution and photo-z shapes in our calibration procedure.
| Type: | Article |
|---|---|
| Title: | Cross-correlation redshift calibration without spectroscopic calibration samples in DES Science Verification Data |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/sty787 |
| Publisher version: | https://doi.org/10.1093/mnras/sty787 |
| Language: | English |
| Additional information: | This is the published version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | galaxies: clusters: general, galaxies: distances and redshifts |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1571429 |
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