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Towards an accurate model of small-scale redshift-space distortions in modified gravity

Ruan, Cheng-Zong; Cuesta-Lazaro, Carolina; Eggemeier, Alexander; Hernández-Aguayo, César; Baugh, Carlton M.; Li, Baojiu; Prada, Francisco

Towards an accurate model of small-scale redshift-space distortions in modified gravity Thumbnail


Cheng-Zong Ruan

Carolina Cuesta-Lazaro

Alexander Eggemeier

César Hernández-Aguayo

Francisco Prada


The coming generation of galaxy surveys will provide measurements of galaxy clustering with unprecedented accuracy and data size, which will allow us to test cosmological models at much higher precision than achievable previously. This means that we must have more accurate theoretical predictions to compare with future observational data. As a first step towards more accurate modelling of the redshift space distortions (RSD) of small-scale galaxy clustering in modified gravity (MG) cosmologies, we investigate the validity of the so-called Skew-T (ST) probability distribution function (PDF) of halo pairwise peculiar velocities in these models. We show that, combined with the streaming model of RSD, the ST PDF substantially improves the small-scale predictions by incorporating skewness and kurtosis, for both cold dark matter (CDM) and two leading MG models: f(R) gravity and the DGP braneworld model. The ST model reproduces the velocity PDF and redshift-space halo clustering measured from MG N-body simulations very well down to ∼ 5 h−1 Mpc. In particular, we investigate the enhancements of halo pairwise velocity moments with respect to CDM for a larger range of MG variants than previous works, and present simple explanations to the behaviours observed. By performing a simple Fisher analysis, we find a significant increase in constraining power to detect modifications of General Relativity by introducing small-scale information in the RSD analyses.

Journal Article Type Article
Acceptance Date May 6, 2022
Online Publication Date May 13, 2022
Publication Date 2022-07
Deposit Date Oct 27, 2021
Publicly Available Date Jun 29, 2022
Journal Monthly Notices of Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 514
Issue 1
Pages 440-459
Public URL
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Published Journal Article (2.8 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2022 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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