Cosmological Evolution in Bimetric Gravity: Observational Constraints and LSS Signatures

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 σ8) 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 ΛCDM model. We reconstructed the " effective dark energy equation of state" (ω de ) and "Skewness" (S3) parameters for the Bimetric model from the observational constraints and show that the current low-redshift data allow significant deviations in ω de and S3 parameters with respect to the ΛCDM behaviour. We also look at the ISW effect via galaxy-temperature correlations and find that the best fit Bimetric model behaves similarly to ΛCDM in this regard.