Probing massive neutrinos and modified gravity with redshift-space morphologies and anisotropies of large-scale structure

TL;DR

This paper demonstrates that non-Gaussian and velocity information from 3D Minkowski functionals and tensors can effectively break the degeneracy between modified gravity models and massive neutrinos in large-scale structure data, improving parameter constraints.

Contribution

It introduces the use of 3D Minkowski functionals and tensors in redshift space to distinguish between modified gravity and neutrino effects, enhancing cosmological parameter constraints.

Findings

Minkowski functionals and tensors can discriminate MG from neutrino effects in redshift space.

Combining power spectrum multipoles with MFs and MTs improves parameter constraints by factors of 1.5 to 3.4.

Anisotropic information enhances the ability to break degeneracies in large-scale structure analysis.

Abstract

Strong degeneracy exists between some modified gravity (MG) models and massive neutrinos because the enhanced structure growth produced by modified gravity can be suppressed due to the free-streaming massive neutrinos. Previous works showed this degeneracy can be broken with non-Gaussian or velocity information. Therefore in this work, we focus on the large-scale structure (LSS) in redshift space and investigate for the first time the possibility of using the non-Gaussian information and velocity information captured by the 3D scalar Minkowski functionals (MFs) and the 3D Minkowski tensors (MTs) to break this degeneracy. Based on the Quijote and Quijote-MG simulations, we find the imprints on redshift space LSS left by the Hu-Sawicki $f(R)$ gravity can be discriminated from those left by massive neutrinos with these statistics. With the Fisher information formalism, we first show how the MTs extract information with their perpendicular and parallel elements for both low- and high-density regions; then we compare constraints from the power spectrum monopole and MFs in real space with those in redshift space, and investigate how the constraining power is further improved with anisotropies captured by the quadrupole and hexadecapole of the power spectrum and the MTs; finally, we combine the power spectrum multipoles with MFs plus MTs and find the constraints from the power spectrum multipoles on $\Omega_{\mathrm{m}}, h, \sigma_8$, $M_\nu$, and $f_{R_0}$ can be improved, because they are complemented with non-Gaussian information, by a factor of 3.4, 3.0, 3.3, 3.3, and 1.9 on small scales ($k_{\rm{max}}=0.5~h\rm{Mpc}^{-1},\ R_G=5~h^{-1}\rm{Mpc}$), and 2.8, 2.2, 3.4, 3.4, and 1.5 on large scales ($k_{\rm{max}}=0.25~h\rm{Mpc}^{-1},\ R_G=10~h^{-1}\rm{Mpc}$).