Breaking Bad Degeneracies with Love: Improving gravitational-wave measurements through universal relations*

The distance-inclination degeneracy limits gravitational-wave parameter estimation of compact binary mergers. Such a degeneracy can be partially broken by including higher-order modes or precession when modeling the waveform of a binary that contains a black hole. But what about binary neutron stars, for which these effects are suppressed? In this talk, I will introduce a new parameterization of the tidal effects in the binary neutron star waveform, exploiting the binary Love relations, that breaks the distance-inclination degeneracy. The binary Love relations prescribe the tidal deformability of a neutron star as a function of its source-frame mass in an equation-of-state insensitive way, and thus allows direct measurement of the redshift of the source. If the cosmological parameters are assumed to be known, the redshift can be converted to a luminosity distance, and the distance-inclination degeneracy can thus be broken. With the distance better constrained, one may also be able to measure the source-frame masses to higher precision. I will demonstrate this new approach with a range of binary neutron-star observing scenarios using Bayesian parameter estimation on synthetic data. In particular, I will give a forecast about when and how much this new approach will improve real gravitational wave measurements of binary neutron stars.