## Abstract / Description of output

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 a Eulerian
galaxy bias expansion using state-of-the-art prescriptions from the
effective field theory of large-scale structure (EFTofLSS) with 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*α* galaxies leading to catalogues of millions of objects within a volume of about 58 *h*^{−3} Gpc^{3}. Our analysis suggests that both models can be used to provide a robust inference of the parameters (*h*, *ω*_{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 –
which includes local and non-local bias parameters, a matter counter
term, and a correction to the shot-noise contribution – can accurately
describe the full shape of the real-space galaxy power spectrum up to
the maximum wavenumber of *k*_{max} = 0.45 *h* Mpc^{−1},
and with a measurement precision of well below the percentage level.
Fixing either of the tidal bias parameters to physically motivated
relations still leads to unbiased cosmological constraints, and helps in
reducing the severity of projection effects due to the large
dimensionality of the model. We finally show how we repeated our
analysis assuming a volume that matches the expected footprint of *Euclid*,
but without considering observational effects, such as purity and
completeness, showing that we can get constraints on the combination (*h*, *ω*_{c})
that are consistent with the fiducial values to better than the 68%
confidence interval over this range of scales and redshifts.

Original language | English |
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Article number | A216 |

Pages (from-to) | 1-40 |

Number of pages | 40 |

Journal | Astronomy and Astrophysics |

Volume | 687 |

DOIs | |

Publication status | Published - 15 Jul 2024 |

## Keywords / Materials (for Non-textual outputs)

- cosmological parameters
- cosmology: theory
- large-scale structure of Universe