Cosmology and perturbations in tachyonic massive gravity

As massive gravity and its extensions offer physically well-defined gravitational theories with a nonzero graviton mass, we present a new extension of the de Rham-Gabadadze-Tolley massive gravity, which is a tachyonic massive gravity theory. We first introduce the new extension of the de Rham-Gabadadze-Tolley massive gravity, constructed by adding a tachyonic term. We then find the cosmological background equations, and present the analysis of self-accelerating solutions. We examine the tensor perturbations to calculate the dispersion relation of gravitational waves (GWs). In a special case, we consider a constant tachyon potential for the tachyon field sigma, V(sigma) = 2 omega=M-Pl(2), and calculate the equations of motion and the self-accelerating solutions. Finally, we investigate the background perturbations, which include tensor, vector, and scalar perturbations in this case. We calculate the dispersion relation of GWs in the FriedmannLemaitre-Robertson-Walker cosmology in a tachyonic massive gravity theory. These analyses provide potential inputs to future applications in cosmology and GW propagations.

Automated summary

This paper introduces a new extension of the de Rham-Gabadadze-Tolley massive gravity, known as tachyonic massive gravity theory. The authors construct this extension by adding a tachyonic term and study the cosmological background equations and self-accelerating solutions. They also analyze the tensor perturbations to calculate the dispersion relation of gravitational waves and investigate the background perturbations in the case of a constant tachyon potential.