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 down-weight 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 fiber-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% fractional decrease on the quadrupole of the 2-point correlation function for projected separations of 40-80 Mpc/h. We also use a halo catalog from the Abacus Summit cosmological simulation suite to reproduce this false quadrupole.
@article{arxiv.2209.03949,
title = {Intrinsic Alignment as an RSD Contaminant in the DESI Survey},
author = {Claire Lamman and Daniel Eisenstein and Jessica Nicole Aguilar and David Brooks and Axel de la Macorra and Peter Doel and Andreu Font-Ribera and Satya Gontcho A Gontcho and Klaus Honscheid and Robert Kehoe and Theodore Kisner and Anthony Kremin and Martin Landriau and Michael Levi and Ramon Miquel and John Moustakas and Nathalie Palanque-Delabrouille and Claire Poppett and Michael Schubnell and Gregory Tarlé},
journal= {arXiv preprint arXiv:2209.03949},
year = {2023}
}
Comments
13 pages, 13 figures. Submitted to MNRAS. For an accessible summary of this paper, see https://cmlamman.github.io/doc/fakeRSD_summary.pdf