Fiducial-Cosmology-dependent systematics for the DESI 2024 BAO Analysis
Abstract
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 for both the isotropic and anisotropic dilation parameters and . We then directly test the impact of the fiducial cosmology on DESI DR1 data.
Keywords
Cite
@article{arxiv.2406.06085,
title = {Fiducial-Cosmology-dependent systematics for the DESI 2024 BAO Analysis},
author = {A. Pérez-Fernández and L. Medina-Varela and R. Ruggeri and M. Vargas-Magaña and H. Seo and N. Padmanabhan and M. Ishak and J. Aguilar and S. Ahlen and S. Alam and O. Alves and U. Andrade and S. Brieden and D. Brooks and A. Carnero Rosell and X. Chen and T. Claybaugh and S. Cole and K. Dawson and A. de la Macorra and A. de Mattia and Arjun Dey and Z. Ding and P. Doel and K. Fanning and C. Garcia-Quintero and E. Gaztañaga and S. Gontcho A Gontcho and G. Gutierrez and K. Honscheid and S. Juneau and D. Kirkby and T. Kisner and A. Lambert and M. Landriau and J. Lasker and L. Le Guillou and M. Manera and P. Martini and A. Meisner and J. Mena-Fernández and R. Miquel and J. Moustakas and A. D. Myers and S. Nadathur and J. A. Newman and G. Niz and E. Paillas and N. Palanque-Delabrouille and W. J. Percival and C. Poppett and F. Prada and M. Rashkovetskyi and A. Rocher and G. Rossi and A. Sanchez and E. Sanchez and M. Schubnell and D. Sprayberry and G. Tarlé and D. Valcin and B. A. Weaver and J. Yu and H. Zou},
journal= {arXiv preprint arXiv:2406.06085},
year = {2025}
}
Comments
Supporting publication of DESI 2024 III: Baryon Acoustic Oscillations from Galaxies and Quasars. Accepted version. Updated references