Dark energy survivals in massive gravity after GW170817: SO(3) invariant

Understand

The recent detection of the gravitational wave signal GW170817 together with an electromagnetic counterpart GRB 170817A from the merger of two neutron stars puts a stringent bound on the tensor propagation speed.

• This constraint can be automatically satisfied in the framework of massive gravity.
• In this work we consider a general $SO(3)$-invariant massive gravity with five propagating degrees of freedom and derive the conditions for the absence of ghosts and Laplacian instabilities in the presence of a matter perfect fluid on the flat Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) cosmological background.
• The graviton potential containing the dependence of three-dimensional metrics and a fiducial metric coupled to a temporal scalar field gives rise to a scenario of the late-time cosmic acceleration in which the dark energy equation of state $w_{\rm DE}$ is equivalent to $-1$ or varies in time.