DESI mock challenge

Halo and galaxy catalogues with the bias assignment method

¹ Instituto de Astrofísica de Canarias, s/n, 38205 La Laguna, Tenerife, Spain
e-mail: balaguera@iac.es
² Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
³ Institue for Astronomy, Royal Observatory, University of Edinburgh, Edinburgh, UK
⁴ Tata Institue of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
⁵ Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305, USA
⁶ Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200233, PR China
⁷ Department of Physics and Astronomy, Università degli Studi di Padova, Vicolo dell’Osservatorio 3, Padova, Italy
⁸ Institute of Physics. Laboratory of astrophysics. École Polytechnique Fédérale de Lausanne, 1290 Lausanne, Switzerland
⁹ Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
¹⁰ Instituto de Física, Universidad Nacional Autónoma de México, Cd. de México C.P., 04510 Mexico city, Mexico
¹¹ Institut de Física d’Altes Energies, The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra, Barcelona, Spain
¹² Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
¹³ Department of Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210, USA
¹⁴ Center for Cosmology and AstroParticle Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210, USA
¹⁵ Department of Physics, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX 75275, USA
¹⁶ NSF’s NOIRLab, 950 N. Cherry Ave., Tucson, AZ 85719, USA
¹⁷ Institució Catalana de Recerca i Estudis Avançats, Passeig de Lluís Companys, 23, 08010 Barcelona, Spain
¹⁸ University of Michigan, Ann Arbor, MI 48109, USA
¹⁹ National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Rd., Chaoyang District, Beijing 100012, PR China

Received: 4 December 2022
Accepted: 16 March 2023

Abstract

Context. We present a novel approach to the construction of mock galaxy catalogues for large-scale structure analysis based on the distribution of dark matter halos obtained with effective bias models at the field level.

Aims. We aim to produce mock galaxy catalogues capable of generating accurate covariance matrices for a number of cosmological probes that are expected to be measured in current and forthcoming galaxy redshift surveys (e.g. two- and three-point statistics). The construction of the catalogues shown in this paper is part of a mock-comparison project within the Dark Energy Spectroscopic Instrument (DESI) collaboration.

Methods. We use the bias assignment method (BAM) to model the statistics of halo distribution through a learning algorithm using a few detailed N-body simulations, and approximated gravity solvers based on Lagrangian perturbation theory. We introduce cosmic-web-dependent corrections to modelling redshift-space distortions at the N-body level – both in the halo and galaxy distributions –, as well as a multi-scale approach for accurate assignment of halo properties. Using specific models of halo occupation distributions to populate halos, we generate galaxy mocks with the expected number density and central-satellite fraction of emission-line galaxies, which are a key target of the DESI experiment.

Results. BAM generates mock catalogues with per cent accuracy in a number of summary statistics, such as the abundance, the two- and three-point statistics of halo distributions, both in real and redshift space. In particular, the mock galaxy catalogues display ∼3%−10% accuracy in the multipoles of the power spectrum up to scales of k ∼ 0.4 h⁻¹Mpc. We show that covariance matrices of two- and three-point statistics obtained with BAM display a similar structure to the reference simulation.

Conclusions. BAM offers an efficient way to produce mock halo catalogues with accurate two- and three-point statistics, and is able to generate a variety of multi-tracer catalogues with precise covariance matrices of several cosmological probes. We discuss future developments of the algorithm towards mock production in DESI and other galaxy-redshift surveys.