Largescale redshift space distortions in modified gravity theories
Abstract
Measurements of redshift space distortions (RSD) provide a means to test models of gravity on large scales. We use mock galaxy catalogues constructed from large Nbody simulations of standard and modified gravity models to measure galaxy clustering in redshift space. We focus our attention on two of the most representative and popular families of modified gravity models: the Hu & Sawicki f(R) gravity and the normal branch of the DvaliGabadadzePorrati (DGP) model. The galaxy catalogues are built using a halo occupation distribution (HOD) prescription with the HOD parameters in the modified gravity models tuned to match with the number density and the realspace clustering of BOSSCMASS galaxies. We employ two approaches to model RSD: the first is based on linear perturbation theory and the second models nonlinear effects on small scales by assuming standard gravity and including biasing and RSD effects. We measure the monopole to realspace correlation function ratio, the quadrupole to monopole ratio, clustering wedges, and multipoles of the correlation function and use these statistics to find the constraints on the distortion parameter, β. We find that the linear model fails to reproduce the Nbody simulation results and the true value of β on scales s < 40 h^{1} Mpc, while the nonlinear modelling of RSD recovers the value of β on the scales of interest for all models. RSD on large scales (s≳ 2040 h^{1} Mpc) have been found to show significant deviations from the prediction of standard gravity in the DGP models. However, the potential to use RSD to constrain f(R) models is less promising, due to the different screening mechanism in this model.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 May 2019
 DOI:
 10.1093/mnras/stz516
 arXiv:
 arXiv:1811.09197
 Bibcode:
 2019MNRAS.485.2194H
 Keywords:

 gravitation;
 methods: data analysis;
 methods: statistical;
 largescale structure of Universe;
 cosmology: theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 18 pages, 11 figures, submitted to MNRAS