Galaxy–Galaxy lensing in HSC: Validation tests and the impact of heterogeneous spectroscopic training sets. Issue 4 (26th October 2019)

• Record Type: Journal Article
• Authors: Speagle, Joshua S; Leauthaud, Alexie; Huang, Song; Bradshaw, Christopher P; Ardila, Felipe; Capak, Peter L; Eisenstein, Daniel J; Masters, Daniel C; Mandelbaum, Rachel; More, Surhud; Simet, Melanie; Sifón, Cristóbal
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 490:Issue 4(2019)
• Page Start: 5658
• Page End: 5677
• Publication Date: 2019-10-26
• Subjects: gravitational lensing: weak -- methods: statistical -- techniques: photometric -- galaxies: distances and redshifts -- cosmology: observations; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz2968
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Although photometric redshifts (photo- z 's) are crucial ingredients for current and upcoming large-scale surveys, the high-quality spectroscopic redshifts currently available to train, validate, and test them are substantially non-representative in both magnitude and colour. We investigate the nature and structure of this bias by tracking how objects from a heterogeneous training sample contribute to photo- z predictions as a function of magnitude and colour, and illustrate that the underlying redshift distribution at fixed colour can evolve strongly as a function of magnitude. We then test the robustness of the galaxy–galaxy lensing signal in 120 deg 2 of HSC–SSP DR1 data to spectroscopic completeness and photo- z biases, and find that their impacts are sub-dominant to current statistical uncertainties. Our methodology provides a framework to investigate how spectroscopic incompleteness can impact photo- z -based weak lensing predictions in future surveys such as LSST and WFIRST .