Euclid preparation. CVIII. Galaxy power spectrum modelling in redshift space

Le résumé fourni par la source

Accurate modelling of redshift-space distortions (RSDs) is essential for maximising the cosmological information extracted from large galaxy redshift surveys. In preparation for the forthcoming analysis of the Euclid spectroscopic data, we investigated three approaches to modelling RSD effects on the power spectrum multipoles of mock Hα emission line galaxies. We focused on two one-loop perturbation theory models -- the effective field theory (EFT) and velocity difference generator ($ ̊m VDG_ ∞ $) -- that differ in their treatment of the real-to-redshift space mapping on small scales and a third approach, the $ and $ model continues to improve parameter constraints beyond ̨max ≳ 0.30 ̨Mpc. The EFT model, although robust on large scales, exhibits significant parameter biases for ̨max ≳ 0.25 ̨Mpc, limiting its applicability to Euclid-like Hα samples. Among the full perturbation theory-based models, the enhanced treatment of small-scale effects of RSDs in $ emulator, that adopts a hybrid strategy combining perturbation theory with high-resolution simulations. We assessed the ability of these models to recover key cosmological parameters, including the expansion rate h, the cold dark matter density parameter omegac, and the scalar amplitude As across four redshift bins spanning 0.9 łeq z łeq 1.8. In each bin, we found that $ ̊m VDG_ ∞ outperform the EFT model across all scales up to ̨max łesssim 0.35 ̨Mpc. While saturates in constraining power at intermediate scales and higher redshift, the $ ̊m VDG_ ∞ ̊m VDG_ ∞ $ improves cosmological parameter constraints by up to a factor of two.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.