Cosmology with cosmic web environments

II. Redshift-space auto and cross-power spectra

¹ Laboratoire de Physique de l’École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, 75005 Paris, France
e-mail: tony.bonnaire@ens.fr
² Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405 Orsay, France
³ Université Paris-Saclay, TAU team INRIA Saclay, CNRS, Laboratoire Interdisciplinaire des Sciences du Numérique, 91190 Gif-sur-Yvette, France
⁴ Departamento de Física Teórica I, Universidad Complutense, 28040 Madrid, Spain

Received: 6 December 2022
Accepted: 19 April 2023

Abstract

Degeneracies among parameters of the cosmological model are known to drastically limit the information contained in the matter distribution. In the first paper of this series, we show that the cosmic web environments, namely the voids, walls, filaments and nodes, can be used as leverage to improve the real-space constraints on a set of six cosmological parameters, including the summed neutrino mass. Following up on these results, we propose to investigate the extent to which constraints can be obtained with environment-dependent power spectra in redshift space where the velocities add information to the standard two-point statistics by breaking the isotropy of the matter density field. A Fisher analysis based on a set of thousands of Quijote simulations allows us to conclude that a combination of power spectra computed in several cosmic web environments is able to break some degeneracies. Compared to the matter monopole and quadrupole information alone, the combination of environment-dependent spectra improves constraints on key parameters such as the matter density and the summed neutrino mass by up to a factor of 5.5. Additionally, while the information contained in the matter statistic quickly saturates at mildly non-linear scales in redshift space, a combination of power spectra from different environments appears to be a rich source of information that can be used to improve the constraints at all the studied scales from 0.1 to 0.5 h Mpc⁻¹ and suggests that further improvements could be attainable at even finer scales.