TY - JOUR

T1 - Euclid preparation. XLI. Galaxy power spectrum modelling in real space

AU - Euclid Collaboration

AU - Collaboration, Euclid

AU - Pezzotta, A.

AU - Moretti, C.

AU - Zennaro, M.

AU - Dizgah, A. Moradinezhad

AU - Crocce, M.

AU - Sefusatti, E.

AU - Ferrero, I.

AU - Pardede, K.

AU - Eggemeier, A.

AU - Barreira, A.

AU - Angulo, R. E.

AU - Marinucci, M.

AU - Quevedo, B. Camacho

AU - Torre, S. de la

AU - Alkhanishvili, D.

AU - Biagetti, M.

AU - Breton, M. -A.

AU - Castorina, E.

AU - D'Amico, G.

AU - Desjacques, V.

AU - Guidi, M.

AU - Kärcher, M.

AU - Oddo, A.

AU - Ibanez, M. Pellejero

AU - Porciani, C.

AU - Pugno, A.

AU - Salvalaggio, J.

AU - Sarpa, E.

AU - Veropalumbo, A.

AU - Vlah, Z.

AU - Amara, A.

AU - Andreon, S.

AU - Auricchio, N.

AU - Baldi, M.

AU - Bardelli, S.

AU - Bender, R.

AU - Bodendorf, C.

AU - Bonino, D.

AU - Branchini, E.

AU - Brescia, M.

AU - Brinchmann, J.

AU - Camera, S.

AU - Capobianco, V.

AU - Markovic, K.

AU - Percival, W. J.

AU - Pollack, J. E.

AU - Joudaki, S.

AU - Nadathur, S.

AU - Pourtsidou, A.

N1 - 38 pages, 19 figures

PY - 2024/7/15

Y1 - 2024/7/15

N2 - We investigate the accuracy of the perturbative galaxy bias expansion in view of the forthcoming analysis of the Euclid spectroscopic galaxy samples. We compare the performance of an Eulerian galaxy bias expansion, using state-of-art prescriptions from the effective field theory of large-scale structure (EFTofLSS), against a hybrid approach based on Lagrangian perturbation theory and high-resolution simulations. These models are benchmarked against comoving snapshots of the Flagship I N-body simulation at $z=(0.9,1.2,1.5,1.8)$, which have been populated with H$\alpha$ galaxies leading to catalogues of millions of objects within a volume of about $58\,h^{-3}\,{\rm Gpc}^3$. Our analysis suggests that both models can be used to provide a robust inference of the parameters $(h, \omega_{\rm c})$ in the redshift range under consideration, with comparable constraining power. We additionally determine the range of validity of the EFTofLSS model in terms of scale cuts and model degrees of freedom. From these tests, it emerges that the standard third-order Eulerian bias expansion can accurately describe the full shape of the real-space galaxy power spectrum up to the maximum wavenumber $k_{\rm max}=0.45\,h\,{\rm Mpc}^{-1}$, even with a measurement precision well below the percent level. In particular, this is true for a configuration with six free nuisance parameters, including local and non-local bias parameters, a matter counterterm, and a correction to the shot-noise contribution. Fixing either tidal bias parameters to physically-motivated relations still leads to unbiased cosmological constraints. We finally repeat our analysis assuming a volume that matches the expected footprint of Euclid, but without considering observational effects, as purity and completeness, showing that we can get consistent cosmological constraints over this range of scales and redshifts.

AB - We investigate the accuracy of the perturbative galaxy bias expansion in view of the forthcoming analysis of the Euclid spectroscopic galaxy samples. We compare the performance of an Eulerian galaxy bias expansion, using state-of-art prescriptions from the effective field theory of large-scale structure (EFTofLSS), against a hybrid approach based on Lagrangian perturbation theory and high-resolution simulations. These models are benchmarked against comoving snapshots of the Flagship I N-body simulation at $z=(0.9,1.2,1.5,1.8)$, which have been populated with H$\alpha$ galaxies leading to catalogues of millions of objects within a volume of about $58\,h^{-3}\,{\rm Gpc}^3$. Our analysis suggests that both models can be used to provide a robust inference of the parameters $(h, \omega_{\rm c})$ in the redshift range under consideration, with comparable constraining power. We additionally determine the range of validity of the EFTofLSS model in terms of scale cuts and model degrees of freedom. From these tests, it emerges that the standard third-order Eulerian bias expansion can accurately describe the full shape of the real-space galaxy power spectrum up to the maximum wavenumber $k_{\rm max}=0.45\,h\,{\rm Mpc}^{-1}$, even with a measurement precision well below the percent level. In particular, this is true for a configuration with six free nuisance parameters, including local and non-local bias parameters, a matter counterterm, and a correction to the shot-noise contribution. Fixing either tidal bias parameters to physically-motivated relations still leads to unbiased cosmological constraints. We finally repeat our analysis assuming a volume that matches the expected footprint of Euclid, but without considering observational effects, as purity and completeness, showing that we can get consistent cosmological constraints over this range of scales and redshifts.

KW - astro-ph.CO

KW - Cosmology:large-scale structure of the Universe

KW - theory

KW - cosmological parameters

KW - galaxy bias

KW - UKRI

KW - MRC

KW - MR/S016066/2

U2 - 10.1051/0004-6361/202348939

DO - 10.1051/0004-6361/202348939

M3 - Article

SN - 0004-6361

VL - 687

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A216

ER -