Cosmological Evolution in Bimetric Gravity: Observational Constraints and LSS Signatures

TL;DR

This paper explores Bimetric gravity as an alternative to General Relativity, analyzing its cosmological implications and observational constraints, and finds it compatible with current data while allowing deviations in dark energy parameters.

Contribution

It provides the first comprehensive observational constraints on Bimetric gravity models, including background expansion, growth of perturbations, and signatures like ISW effect.

Findings

Bimetric models are consistent with current low-redshift data.

Significant deviations in dark energy parameters are possible within Bimetric models.

Bimetric models mimic $\Lambda$CDM$ behavior in ISW effect observations.

Abstract

Bimetric gravity is an interesting alternative to standard GR given its potential to provide a concrete theoretical framework for a ghost-free massive gravity theory. Here we investigate a class of Bimetric gravity models for their cosmological implications. We study the background expansion as well as the growth of matter perturbations at linear and second order. We use low-redshift observations from SnIa (Pantheon+ and SH0ES), Baryon Acoustic Oscillations (BAO), the growth ($f\sigma_{8}$) measurements and the measurement from Megamaser Cosmology Project to constrain the Bimetric model. We find that the Bimetric models are consistent with the present data alongside the $\Lambda$CDM model. We reconstructed the `` effective dark energy equation of state" ($\omega_{de}$) and "Skewness" ($S_{3}$) parameters for the Bimetric model from the observational constraints and show that the current low-redshift data allow significant deviations in $\omega_{de}$ and $S_{3}$ parameters with respect to the $\Lambda$CDM behaviour. We also look at the ISW effect via galaxy-temperature correlations and find that the best fit Bimetric model behaves similarly to $\Lambda$CDM in this regard.