Fiducial-cosmology-dependent systematics for the DESI 2024 BAO analysis

Journal Article · Thu Jan 30 00:00:00 UTC 2025 · Journal of Cosmology and Astroparticle Physics

DOI: https://doi.org/10.1088/1475-7516/2025/01/144 · OSTI ID:3011035

Pérez-Fernández, A. ; Medina-Varela, L.; Ruggeri, R. ; Vargas-Magaña, M. ; Seo, H. ; Padmanabhan, N.; Ishak, M. ; Aguilar, J.; Ahlen, S. ; Alam, S. ; Alves, O.; Andrade, U. ; Brieden, S. ; Brooks, D.; Carnero Rosell, A. ; Chen, X. ; Claybaugh, T.; Cole, S. ; Dawson, K.; de la Macorra, A. ; de Mattia, A. ; Dey, Arjun ; Ding, Z. ; Doel, P.; Fanning, K. ; Garcia-Quintero, C. ; Gaztañaga, E.; Gontcho, S.Gontcho A. ; Gutierrez, G.; Honscheid, K.; Juneau, S.; Kirkby, D. ; Kisner, T. ; Lambert, A.; Landriau, M. ; Lasker, J. ; Le Guillou, L. ; Manera, M. ; Martini, P. ; Meisner, A. ; Mena-Fernández, J. ; Miquel, R.; Moustakas, J. ; Myers, A.D.; Nadathur, S. ; Newman, J.A. ; Niz, G. ; Paillas, E. ; Palanque-Delabrouille, N. ; Percival, W.J. ; Poppett, C.; Prada, F. ; Rashkovetskyi, M. ; Rocher, A. ; Rossi, G.; Sanchez, A.; Sanchez, E. ; Schubnell, M.; Sprayberry, D.; Tarlé, G. ; Valcin, D. ; Weaver, B.A.; Yu, J. ; Zou, H.

When measuring the Baryon Acoustic Oscillations (BAO) scale from galaxy surveys, one typically assumes a fiducial cosmology when converting redshift measurements into comoving distances and also when defining input parameters for the reconstruction algorithm. A parameterised template for the model to be fitted is also created based on a (possibly different) fiducial cosmology. This model reliance can be considered a form of data compression, and the data is then analysed allowing that the true answer is different from the fiducial cosmology assumed. In this study, we evaluate the impact of the fiducial cosmology assumed in the BAO analysis of the Dark Energy Spectroscopic Instrument (DESI) survey Data Release 1 (DR1) on the final measurements in DESI 2024 III. We utilise a suite of mock galaxy catalogues with survey realism that mirrors the DESI DR1 tracers: the bright galaxy sample (BGS), the luminous red galaxies (LRG), the emission line galaxies (ELG) and the quasars (QSO), spanning a redshift range from 0.1 to 2.1. We compare the four secondary AbacusSummit cosmologies against DESI's fiducial cosmology (Planck 2018). The secondary cosmologies explored include a lower cold dark matter density, a thawing dark energy universe, a higher number of effective species, and a lower amplitude of matter clustering. The mocks are processed through the BAO pipeline by consistently iterating the grid, template, and reconstruction reference cosmologies. We determine a conservative systematic contribution to the error of 0.1% for both the isotropic and anisotropic dilation parameters αiso and αAP. We then directly test the impact of the fiducial cosmology on DESI DR1 data.

• Research Organization: BCCP, Berkeley; Barcelona, Autonoma U.; Barcelona, IEEC; Barcelona, IFAE; Beijing Observ.; Boston U.; Chicago U., KICP; Durham U., ICC; Ecole Polytechnique, Lausanne; Edinburgh U., Inst. Astron.; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Garching, Max Planck Inst., MPE; Granada U., Theor. Phys. Astrophys.; Guanajuato U.; Harvard-Smithsonian Ctr. Astrophys.; Hiroshima Shudo U.; IAC, La Laguna; ICREA, Barcelona; IRFU, Saclay; KEK, Tsukuba; LPNHE, Paris; LPSC, Grenoble; Laguna U., Tenerife; Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Madrid, CIEMAT; Mexico U., ICN; Michigan U.; Natl. Solar Observ., Tucson; Ohio State U.; Ohio State U., Dept. Astron.; Ohio U., Athens; Ohio University, Athens, OH (United States); Perimeter Inst. Theor. Phys.; Pittsburgh U.; Portsmouth U., ICG; Queensland U.; SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Sejong U.; Shanghai Jiaotong U.; Siena Coll., Loudonville; Southern Methodist U.; Swinburne U., Ctr. Astrophys. Supercomput.; TIFR, Mumbai, DHEP; U. Michigan, Ann Arbor; U. Texas, Dallas; UC, Berkeley (main); UC, Irvine; UNAM, Mexico; Univ. of Utah, Salt Lake City, UT (United States); University Coll. London; University of Michigan, Ann Arbor, MI (United States); Utah U.; Waterloo U.; Wyoming U.; Yale U.
• Sponsoring Organization: Proyecto PIFF and Proyecto Investigación in Ciencia Básica CONAHCYT; U.S. National Science Foundation (NSF), Division of Astronomical Sciences; US Department of Energy; USDOE Office of Science (SC), High Energy Physics (HEP); USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• Contributing Organization: DESI; DESI Collaboration
• Grant/Contract Number: 89243024CSC000002; AC02-05CH11231; SC0009959; SC0019091; SC0019193; SC0023241
• OSTI ID: 3011035
• Report Number(s): FERMILAB-PUB-24-0613-PPD
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 01 Vol. 2025; ISSN 1475-7516
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English