Gravitational waves from inspiralling compact binaries in conformal gravity

Abstract: We investigate the production of gravitational waves during the inspiral of compact binaries close to their merger in the context of a conformal gravity model. The model incorporates five massive polarization degrees of freedom, besides the two massless gravitational wave polarizations of general relativity. For small graviton mass, we find that the amplitude of the gravitational waves is strongly suppressed as compared to general relativity and decreases as coalescence is approached, which contradicts the observational fact. We conclude that this model with small graviton mass, including a regime that can explain galaxy rotation curves without dark matter, cannot describe the observed gravitational wave events. For a large graviton mass, the modifications to the waveform, compared to the one from general relativity, are negligible on the relevant distance scales and hence a conformal gravity model with a large graviton mass is in agreement with LIGO/VIRGO observations and leads to chirp mass and distance estimates that agree with those from general relativity.