Cosmological behavior in extended nonlinear massive gravity

TL;DR

This paper analyzes the cosmological implications of extended nonlinear massive gravity, showing it can produce diverse late-time behaviors like quintessence or phantom solutions, potentially addressing the coincidence problem.

Contribution

It provides a detailed dynamical analysis demonstrating the rich solution space of extended nonlinear massive gravity, which was less explored compared to standard models.

Findings

Allows for quintessence, phantom, or cosmological-constant-like solutions

Can alleviate the coincidence problem

Features are robust across different model assumptions

Abstract

We perform a detailed dynamical analysis of various cosmological scenarios in extended (varying-mass) nonlinear massive gravity. Due to the enhanced freedom in choosing the involved free functions, this cosmological paradigm allows for a huge variety of solutions that can attract the universe at late times, comparing to scalar-field cosmology or usual nonlinear massive gravity. Amongst others, it accepts quintessence, phantom, or cosmological-constant-like late-time solutions, which moreover can alleviate the coincidence problem. These features seem to be general and non-sensitive to the imposed ansantzes and model parameters, and thus extended nonlinear massive gravity can be a good candidate for the description of nature.