Constraints on bimetric gravity. Part II. Observational constraints

Ghost-free bimetric gravity is a theory of two interacting spin-2 fields, one massless and massive, in addition to the standard matter particles thereby generalizing Einstein's general relativity. To parameterize theory, we use five observables with specific physical interpretations. We present, for first time, observational constraints on these parameters that: (i) apply full (ii) are consistent working screening mechanism (i.e., restoring relativity locally), (iii) exhibit continuous, real-valued background cosmology (without Higuchi ghost). For cosmological constraints, data sets from cosmic microwave background, baryon acoustic oscillations, type Ia supernovae. Bimetric provides good fit even large values mixing angle between massive gravitons. Interestingly, best-fit model self-accelerating solution where accelerated expansion due dynamical field, without constant. Due mechanism, models local tests such as solar system gravitational lensing by galaxies. also comment possibility alleviating Hubble tension this theory.