Dark matter in ghost-free bigravity theory: From a galaxy scale to the universe

TL;DR

This paper explores how ghost-free bigravity theory with twin matter fluids can account for dark matter phenomena and cosmic acceleration, providing a unified framework for galactic and cosmological observations.

Contribution

It demonstrates that bigravity theory with twin matter fluids can simultaneously explain dark matter effects and cosmic acceleration by appropriate parameter tuning.

Findings

Bigravity theory can account for galactic missing mass.

Cosmic acceleration explained by graviton mass.

Dark matter effects modeled by twin matter fluids.

Abstract

We study the origin of dark matter based on the ghost-free bigravity theory with twin matter fluids. The present cosmic acceleration can be explained by the existence of graviton mass, while dark matter is required in several cosmological situations [the galactic missing mass, the cosmic structure formation and the standard big-bang scenario (the cosmological nucleosynthesis vs the CMB observation)]. Assuming that the Compton wavelength of the massive graviton is shorter than a galactic scale, we show the bigravity theory can explain dark matter by twin matter fluid as well as the cosmic acceleration by tuning appropriate coupling constants.