Strong constraints on cosmological gravity from GW170817 and GRB 170817A

TL;DR

The paper uses the neutron star merger event GW170817 and its electromagnetic counterpart to place tight constraints on alternative theories of gravity, significantly narrowing the range of viable cosmological models beyond general relativity.

Contribution

It provides new, stringent bounds on scalar-tensor, vector-tensor, and bimetric gravity theories using multimessenger observations.

Findings

Severe restrictions on scalar-tensor and vector-tensor theories.

Independent bounds on the graviton mass in bimetric theories.

Reduced viability of alternative cosmological models.

Abstract

The detection of an electromagnetic counterpart (GRB 170817A) to the gravitational wave signal (GW170817) from the merger of two neutron stars opens a completely new arena for testing theories of gravity. We show that this measurement allows us to place stringent constraints on general scalar-tensor and vector-tensor theories, while allowing us to place an independent bound on the graviton mass in bimetric theories of gravity. These constraints severely reduce the viable range of cosmological models that have been proposed as alternatives to general relativistic cosmology.