Intrinsic Alignment as an RSD Contaminant in the DESI Survey

Claire Lamman; Daniel Eisenstein; Jessica Nicole Aguilar; David Brooks; Axel de la Macorra; Peter Doel; Andreu Font-Ribera; Satya Gontcho A Gontcho; Klaus Honscheid; Robert Kehoe; Theodore Kisner; Anthony Kremin; Martin Landriau; Michael Levi; Ramon Miquel; John Moustakas; Nathalie Palanque-Delabrouille; Claire Poppett; Michael Schubnell; Gregory Tarlé

doi:10.1093/mnras/stad950

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arXiv · 2209.03949

Intrinsic Alignment as an RSD Contaminant in the DESI Survey

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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 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.

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Claire Lamman, Daniel Eisenstein, Jessica Nicole Aguilar, David Brooks, Axel de la Macorra, Peter Doel, Andreu Font-Ribera, Satya Gontcho A Gontcho, Klaus Honscheid, Robert Kehoe, Theodore Kisner, Anthony Kremin, Martin Landriau, Michael Levi, Ramon Miquel, John Moustakas, Nathalie Palanque-Delabrouille, Claire Poppett, Michael Schubnell, Gregory Tarlé. 2022-09-08. Intrinsic Alignment as an RSD Contaminant in the DESI Survey. https://doi.org/10.1093/mnras%2Fstad950

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