Title: Questioning the viability of bigravity cosmology
Abstract:Bigravity is an extension of dRGT massive gravity which arises by promoting the background reference metric of dRGT massive gravity to a dynamical quantity. In the context of the low energy limit model, which is the only viable bigravity model distinguishable from GR, we study linear and non-linear perturbations and identify the Vainshtein radius, below which non-linear scalar self interactions conspire to reproduce GR on local scales. We combine this result, with the requirement of the existence of a late-time de-Sitter attractor and matching the observed value of the cosmological constant to the effective cosmological constant derived from the theory, to identify a parameter space which is compatible with observations. We find that the requirement on having a successful Vainsthein mechanism is not compatible with cosmological solutions at early times.