Intrinsic alignment as an RSD contaminant in the DESI survey

• Published in: Monthly notices of the Royal Astronomical Society Vol. 522; no. 1; pp. 117 - 129
• Main Authors: Lamman, Claire, Eisenstein, Daniel, Aguilar, Jessica Nicole, Brooks, David, de la Macorra, Axel, Doel, Peter, Font-Ribera, Andreu, Gontcho A Gontcho, Satya, Honscheid, Klaus, Kehoe, Robert, Kisner, Theodore, Kremin, Anthony, Landriau, Martin, Levi, Michael, Miquel, Ramon, Moustakas, John, Palanque-Delabrouille, Nathalie, Poppett, Claire, Schubnell, Michael, Tarlé, Gregory
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 13.04.2023; Oxford University Press (OUP): Policy P - Oxford Open Option A
• Subjects: ASTRONOMY AND ASTROPHYSICS; Astrophysics; cosmological observations; dark energy; data analysis; large-scale structure of the universe; Physics; cosmology: observations; methods: data analysis; dark energy; large-scale structure of Universe
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stad950

ABSTRACT We measure the tidal alignment of the major axes of luminous red galaxies (LRGs) from the Legacy Imaging Survey and use it to infer the artificial redshift-space distortion signature that will arise from an orientation-dependent, surface-brightness selection in the Dark Energy Spectroscopic Instrument (DESI) survey. Using photometric redshifts to downweight the shape–density correlations due to weak lensing, we measure the intrinsic tidal alignment of LRGs. Separately, we estimate the net polarization of LRG orientations from DESI’s fibre-magnitude target selection to be of order 10−2 along the line of sight. Using these measurements and a linear tidal model, we forecast a 0.5 per cent fractional decrease on the quadrupole of the two-point correlation function for projected separations of 40–80 h−1 Mpc. We also use a halo catalogue from the Abacussummit cosmological simulation suite to reproduce this false quadrupole.