The DESI One-Percent Survey: Modelling the clustering and halo occupation of all four DESI tracers with UCHUU

Journal Article · Fri Jun 13 00:00:00 UTC 2025 · Astronomy and Astrophysics

DOI: https://doi.org/10.1051/0004-6361/202451022 · OSTI ID:3009767

Prada, F. ; Ereza, J. ; Smith, A.; Lasker, J. ; Vaisakh, R. ; Kehoe, R.; Dong-Páez, C. A.; Siudek, M. ; Wang, M. S. ; Alam, S.; Beutler, F. ; Bianchi, D.; Cole, S. ; Dey, B. ; Kirkby, D. ; Norberg, P. ; Aguilar, J. ; Ahlen, S.; Brooks, D. ; Claybaugh, T. ; Dawson, K. ; de la Macorra, A.; Fanning, K.; Forero-Romero, J. E. ; Gontcho A Gontcho, S.; Hahn, C.; Honscheid, K.; Ishak, M.; Kisner, T.; Landriau, M.; Manera, M. ; Meisner, A. ; Miquel, R. ; Moustakas, J. ; Mueller, E.; Nie, J.; Percival, W. J. ; Poppett, C.; Rezaie, M.; Rossi, G.; Sanchez, E. ; Schubnell, M.; Tarlé, G.; Vargas-Magaña, M.; Weaver, B. A.; Yuan, S.; Zhou, Z.

We present results from a set of mock lightcones for the DESI One-Percent Survey, created from the UCHUU simulation. This 8 h⁻³ Gpc³ N-body simulation comprises 2.1 trillion particles and provides high-resolution dark matter (sub)haloes in the framework of the Planck-based ΛCDM cosmology. Employing the subhalo abundance matching (SHAM) technique, we populated the UCHUU (sub)haloes with all four DESI tracers – Bright Galaxy Survey (BGS), luminous red galaxies (LRGs), emission line galaxies (ELGs), and quasars (QSOs) – to z = 2.1. Our method accounts for redshift evolution as well as the clustering dependence on luminosity and stellar mass. The two-point clustering statistics of the DESI One-Percent Survey generally agree with predictions from UCHUU across scales ranging from 0.3 h⁻¹ Mpc to 100 h⁻¹ Mpc for the BGS and across scales ranging from 5 h⁻¹ Mpc to 100 h⁻¹ Mpc for the other tracers. We observed some differences in clustering statistics that can be attributed to incompleteness of the massive end of the stellar mass function of LRGs, our use of a simplified galaxy-halo connection model for ELGs and QSOs, and cosmic variance. We find that at the high precision of UCHUU, the shape of the halo occupation distribution (HOD) of the BGS and LRG samples is smaller bias values, likely due to cosmic variance. The bias dependence on absolute magnitude, stellar mass, and redshift aligns with that of previous surveys. These results provide DESI with tools to generate high-fidelity lightcones for the remainder of the survey and enhance our understanding of the galaxy-halo connection.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Univ. of Michigan, Ann Arbor, MI (United States); Univ. of Utah, Salt Lake City, UT (United States)
• Sponsoring Organization: US Department of Energy; USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF); USDOE Office of Science (SC), High Energy Physics (HEP); USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• Grant/Contract Number: AC02-05CH11231; AC02-76SF00515; SC0009959; SC0010129; SC0019193
• OSTI ID: 3009767
• Journal Information: Astronomy and Astrophysics, Journal Name: Astronomy and Astrophysics Vol. 698; ISSN 1432-0746; ISSN 0004-6361
• Publisher: EDP SciencesCopyright Statement
• Country of Publication: United States
• Language: English