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Effects of Symmetron on growth and RSD multipoles

Gerardo Morales-Navarrete, Jorge L. Cervantes-Cota

Abstract

In this work, we investigate the effects of the growth rate scale dependence in the Symmetron modified gravity (MG) model on cosmic structure formation and we analyze the redshift-space distortion (RSD) multipoles, comparing with the Hu-Sawicki $f(R)$ model (specifically the F6) and the standard $Λ$CDM model. The analysis employs a scale-dependent growth equation and utilizes the fk-PT perturbation theory approach, implemented in the FOLPS-nu code, to compute the full 1-loop power spectrum multipoles, in particular, the monopole and quadrupole ($\ell=0,2$, respectively). The results show that at redshift $z=0$, the monopole of both MG models is suppressed compared to $Λ$CDM, with the Symmetron being closer to the standard model, while the quadrupole presents the opposite behavior. To validate the pipeline, we use General Relativity (GR) mock catalogs (EZMocks), since suitable Symmetron simulations are not available. The main result is that the Markov Chain Monte Carlo (MCMC) analysis successfully recovers the expected GR limit (i.e., $β_0 \approx 0$) from the Symmetron model when applied to this mock data, confirming the viability of our methodology for cosmological inference. Then, we conclude that the pipeline is prepared to test MG models against current and near-future galaxy surveys.

Effects of Symmetron on growth and RSD multipoles

Abstract

In this work, we investigate the effects of the growth rate scale dependence in the Symmetron modified gravity (MG) model on cosmic structure formation and we analyze the redshift-space distortion (RSD) multipoles, comparing with the Hu-Sawicki model (specifically the F6) and the standard CDM model. The analysis employs a scale-dependent growth equation and utilizes the fk-PT perturbation theory approach, implemented in the FOLPS-nu code, to compute the full 1-loop power spectrum multipoles, in particular, the monopole and quadrupole (, respectively). The results show that at redshift , the monopole of both MG models is suppressed compared to CDM, with the Symmetron being closer to the standard model, while the quadrupole presents the opposite behavior. To validate the pipeline, we use General Relativity (GR) mock catalogs (EZMocks), since suitable Symmetron simulations are not available. The main result is that the Markov Chain Monte Carlo (MCMC) analysis successfully recovers the expected GR limit (i.e., ) from the Symmetron model when applied to this mock data, confirming the viability of our methodology for cosmological inference. Then, we conclude that the pipeline is prepared to test MG models against current and near-future galaxy surveys.
Paper Structure (4 sections, 2 equations, 2 figures)

This paper contains 4 sections, 2 equations, 2 figures.

Table of Contents

  1. Introduction
  2. Growth rate scale dependency
  3. 1-loop RSD MG multipoles
  4. Model validation with GR mocks

Figures (2)

  • Figure 1: Monopole ($\ell=0$) and quadrupole ($\ell=2$) at $z=0$ for the Symmetron, Hu-Sawicki F6, and $\Lambda$CDM models.
  • Figure 2: Confidence level contours for Symmetron model using EZMocks at $z=0$, using the monopole and quadrupole. The $\beta_0$ parameter was considered free with a flat prior $\mathcal{U}(-0.01,0.01)$ as similar as $f_{R0}$ for $f(R)$ in Appendix B of Ref. moralesnavarrete2025fullshapepowerspectrumsymmetron. Dashed lines mark EZMocks parameter simulation values.