DOE OSTI · 3007048
Exploring HOD-dependent systematics for the DESI 2024 Full-Shape galaxy clustering analysis
Abstract
We analyze the robustness of the DESI 2024 cosmological inference from the full shape of the galaxy power spectrum to uncertainties in the Halo Occupation Distribution (HOD) model of the galaxy-halo connection and the choice of priors on nuisance parameters. We assess variations in the recovered cosmological parameters across a range of mocks populated with different HOD models and find that shifts are often greater than 20% of the expected statistical uncertainties from the DESI data. We encapsulate the effect of such shifts in terms of a systematic covariance term, C HOD , and an additional diagonal contribution quantifying the impact of our choice of nuisance parameter priors on the ability of the effective field theory (EFT) model to correctly recover the cosmological parameters of the simulations. These two covariance contributions are designed to be added to the usual covariance term, C stat , describing the statistical uncertainty in the power spectrum measurement, in order to fairly represent these sources of systematic uncertainty. This novel approach should be more general and robust to the choice of model or additional external datasets used in cosmological fits than the alternative approach of adding systematic uncertainties to the recovered marginalised parameter posteriors. We compare the approaches within the context of a fixed ΛCDM model and demonstrate that our method gives conservative estimates of the systematic uncertainty that nevertheless have little impact on the final posteriors obtained from DESI data.
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Findlay, Nathan [University of Portsmouth (United Kingdom)] (ORCID:0009000707163477), Nadathur, S. [University of Portsmouth (United Kingdom)] (ORCID:0000000190703102), Percival, W. J. [University of Waterloo, ON (Canada); Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada)] (ORCID:0000000206445727), de Mattia, A. [Université Paris-Saclay, Gif-sur-Yvette (France)] (ORCID:0000000309202947), Zarrouk, P. [Sorbonne Université, Paris (France)] (ORCID:0000000273059578), Gil-Marín, H. [Universitat de Barcelona (Spain); Institut d'Estudis Espacials de Catalunya (IEEC), Barcelona (Spain)] (ORCID:0000000302656217), Alves, O. [University of Michigan, Ann Arbor, MI (United States)], Mena-Fernández, J. [Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France)] (ORCID:0000000194977266), Garcia-Quintero, C. [Harvard & Smithsonian, Cambridge, MA (United States); The University of Texas at Dallas, Richardson, TX (United States)] (ORCID:0000000314814294), Rocher, A. [Ecole Polytechnique Fédérale de Lausanne (Switzerland); Université Paris-Saclay, Gif-sur-Yvette (France)] (ORCID:0000000343496424), Ahlen, S. [Boston University, MA (United States)] (ORCID:0000000160987247), Bianchi, D. [Università degli Studi di Milano (Italy)] (ORCID:0000000197120006), Brooks, D. [University College London (United Kingdom)], Claybaugh, T. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Cole, S. [Durham University (United Kingdom)] (ORCID:0000000259547903), de la Macorra, A. [Universidad Nacional Autónoma de México (Mexico)] (ORCID:0000000217691640), Dey, A. [NSF NOIRLab, Tucson, AZ (United States)] (ORCID:0000000249284003), Doel, P. [University College London (United Kingdom)], Fanning, K. [Stanford University, Menlo Park, CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000323713356), Font-Ribera, A. [University College London (United Kingdom); The Barcelona Institute of Science and Technology, Bellaterra Barcelona (Spain)] (ORCID:0000000230337312), Forero-Romero, J. E. [Universidad de los Andes, Bogotá (Colombia)] (ORCID:0000000228903725), Gaztañaga, E. [Institut d'Estudis Espacials de Catalunya (IEEC), Barcelona (Spain); University of Portsmouth (United Kingdom); Institute of Space Sciences, Barcelona (Spain)], Gutierrez, G. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)], Hahn, C. [Princeton University, NJ (United States)] (ORCID:0000000311970902), Honscheid, K. [The Ohio State University, Columbus, OH (United States)], Howlett, C. [University of Queensland (Australia)] (ORCID:0000000210819410), Juneau, S. [NSF NOIRLab, Tucson, AZ (United States)], Levi, M. E. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000318871018), Meisner, A. [NSF NOIRLab, Tucson, AZ (United States)] (ORCID:0000000211257384), Miquel, R. [Institució Catalana de Recerca i Estudis Avançats, Barcelona (Spain); The Barcelona Institute of Science and Technology, Bellaterra Barcelona (Spain)], Moustakas, J. [Siena College, Loudonville, NY (United States)] (ORCID:0000000227334559), Palanque-Delabrouille, N. [Université Paris-Saclay, Gif-sur-Yvette (France); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:000000033188784X), Pérez-Ràfols, I. [Universitat Politècnica de Catalunya, Barcelona (Spain)] (ORCID:0000000169790125), Rossi, G. [Sejong University, Seoul (Korea)], Sanchez, E. [CIEMAT, Madrid (Spain)] (ORCID:0000000296468198), Schlegel, D. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Schubnell, M. [University of Michigan, Ann Arbor, MI (United States)], Seo, H. [Ohio University, Athens, OH (United States)] (ORCID:0000000265883508), Sprayberry, D. [NSF NOIRLab, Tucson, AZ (United States)], Tarlé, G. [University of Michigan, Ann Arbor, MI (United States)] (ORCID:0000000317040781), Vargas-Magaña, M. [Universidad Nacional Autónoma de México (Mexico)] (ORCID:0000000338411836), Weaver, B. A. [NSF NOIRLab, Tucson, AZ (United States)]. 2025-09-01. Exploring HOD-dependent systematics for the DESI 2024 Full-Shape galaxy clustering analysis. https://doi.org/10.1088/1475-7516%2F2025%2F09%2F007
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