EFTCAMB/EFTCosmoMC: massive neutrinos in dark cosmologies

TL;DR

This paper investigates the degeneracy between massive neutrinos and modified gravity theories using effective field theory, providing tighter constraints on f(R) models and setting new bounds on neutrino mass and gravity parameters.

Contribution

It introduces an updated EFTCAMB/EFTCosmoMC code that accurately models massive neutrinos and modified gravity, improving bounds and analyzing degeneracies.

Findings

Tighter bounds on f(R) gravity parameters.

Looser bounds on the sum of neutrino masses.

No significant degeneracy observed between neutrinos and non-minimal gravity models.

Abstract

We revisit the degeneracy between massive neutrinos and generalized theories of gravity in the framework of effective field theory of cosmic acceleration. In particular we consider f(R) theories and a class of non-minimally coupled models parametrized via a coupling to gravity which is linear in the scale factor. In the former case, we find a slightly lower degeneracy with respect to what found so far in the literature, due to the fact that we implement exact designer f(R) models and evolve the full linear dynamics of perturbations. As a consequence, our bounds are slightly tighter on the f(R) parameter but looser on the summed neutrino mass. We also set a new upper bound on the Compton wavelength parameter ${\rm Log}_{10}B_0<-4.1$ at 95% C.L. with fixed summed neutrino mass ($\sum m_{\nu}=0.06$ eV) in f(R) gravity with the combined data sets from cosmic microwave background temperature and lensing power spectra of Planck collaboration as well as galaxy power spectrum from WiggleZ dark energy survey. We do not observe a sizable degeneracy between massive neutrinos and modified gravity in the linear parametrization of non-minimally gravitational coupling model. The analysis is performed with an updated version of the EFTCAMB/EFTCosmoMC package, which is now publicly available and extends the first version of the code with the consistent inclusion of massive neutrinos, tensor modes, several alternative background histories and designer quintessence models.