DESI luminous red galaxy samples for cross-correlations

TL;DR

This paper introduces two galaxy samples from DESI Legacy Imaging Surveys optimized for cross-correlation studies with CMB lensing, galaxy lensing, and Sunyaev-Zel'dovich effect, including improved redshift estimates and systematics corrections.

Contribution

The paper provides new galaxy samples with enhanced photometric redshifts, systematic weights, and magnification bias coefficients, tailored for cross-correlation cosmology, and makes these data publicly available.

Findings

Two galaxy samples covering 20,000 sq. degrees for cross-correlation studies.

Improved photometric redshifts and systematic weights for the samples.

Public release of catalogs and redshift data for community use.

Abstract

We present two galaxy samples, selected from DESI Legacy Imaging Surveys (LS) DR9, with approximately 20,000 square degrees of coverage and spectroscopic redshift distributions designed for cross-correlations such as with CMB lensing, galaxy lensing, and the Sunyaev-Zel'dovich effect. The first sample is identical to the DESI Luminous Red Galaxy (LRG) sample, and the second sample is an extended LRG sample with 2-3 times the DESI LRG density. We present the improved photometric redshifts, tomographic binning and their spectroscopic redshift distributions and imaging systematics weights, and magnification bias coefficients. The catalogs and related data products will be made publicly available. The cosmological constraints using this sample and Planck lensing maps are presented in a companion paper. We also make public the new set of general-purpose photometric redshifts trained using DESI spectroscopic redshifts, which are used in this work, for all galaxies in LS DR9.