Does GW170817 falsify MOND?

TL;DR

The paper argues that the GW170817 event challenges certain modified gravity theories like TeVeS by showing they predict different delays for light and gravitational waves, thus constraining their validity.

Contribution

It demonstrates that GW170817 rules out a class of relativistic MOND extensions that rely solely on modified field equations without extra matter-coupling fields.

Findings

GW170817 rules out TeVeS and similar theories

Modified gravity theories predicting different gravitational and electromagnetic delays are falsified

Constraints favor theories with additional matter-coupling fields

Abstract

The gravitational-wave event GW170817 and the near-simultaneous corresponding gamma-ray burst (GRB 170817 A) falsify modified gravity theories in which the gravitational geometry differs non-conformally from physical geometry. Thus, the observations of this event definitively rule out theories, such as TeVeS, a suggested relativistic extension of Milgrom's modified Newtonian dynamics (MOND), that predict a significantly different Shapiro delay for electromagnetic and gravitational radiation. While not falsifying MOND per se, GW170817 severely constrains relativistic extensions of MOND to theories that do not rely on additional matter-coupling fields but rather upon modified field equations for one universal gravitational and physical metric. Here I mention a simple preferred-frame theory as an example.