New Cosmological Solutions in Massive Gravity

Tsutomu Kobayashi, Masaru Siino, Masahide Yamaguchi, Daisuke Yoshida

Published 2012-05-22Version 1

We find new, simple cosmological solutions with flat, open, and closed spatial geometries, contrary to the previous wisdom that only the open model is allowed. The metric and the St\"{u}ckelberg fields are given explicitly, showing nontrivial configurations of the St\"{u}ckelberg in the usual Friedmann-Lema\^{i}tre-Robertson-Walker coordinates. The solutions exhibit self-acceleration, while being free from ghost instabilities. Our solutions can accommodate inhomogeneous dust collapse represented by the Lema\^{i}tre-Tolman-Bondi metric as well. Thus, our results can be used not only to describe homogeneous and isotropic cosmology but also to study gravitational collapse in massive gravity.