Joint halo mass function for modified gravity and massive neutrinos I: simulations and cosmological forecasts

TL;DR

This paper develops an accurate halo mass function for modified gravity models with massive neutrinos, calibrated with simulations, and assesses how galaxy cluster observations can detect deviations from general relativity and constrain neutrino mass.

Contribution

It introduces a calibrated halo mass function for Hu-Sawicki $f(R)$ models with neutrinos, based on spherical collapse and N-body simulations, advancing cosmological tests of gravity.

Findings

Current cluster observations face degeneracy between gravity modifications and neutrino effects.

Future surveys can break this degeneracy and improve constraints on modified gravity and neutrino mass.

The halo mass function model enhances the accuracy of cosmological forecasts in modified gravity scenarios.

Abstract

We present a halo mass function accurate over the full relevant Hu-Sawicki $f(R)$ parameter space based on spherical collapse calculations and calibrated to a suite of modified gravity $N$-body simulations that include massive neutrinos. We investigate the ability of current and forthcoming galaxy cluster observations to detect deviations from general relativity while constraining the total neutrino mass and including systematic uncertainties. Our results indicate that the degeneracy between massive neutrino and modify gravity effects is a limiting factor for the current searches for new gravitational physics with clusters of galaxies, but future surveys will be able to break the degeneracy.