Binary Love Relations

TL;DR

This paper discovers approximately universal relations between neutron star tidal deformabilities in binary systems, enabling more accurate gravitational wave measurements and better insights into dense matter physics and gravity theories.

Contribution

It introduces new universal relations that break degeneracies in gravitational wave data, allowing precise extraction of individual neutron star tidal deformabilities.

Findings

Universal relations between tidal deformabilities were identified.

These relations improve the extraction accuracy of neutron star properties from gravitational waves.

Enhanced ability to test equations of state and gravity theories using gravitational wave observations.

Abstract

When in a tight binary, the mutual tidal deformations of neutron stars imprint onto observables, encoding information about their internal structure at supranuclear densities and gravity in the extreme-gravity regime. Gravitational wave observations of their late binary inspiral may serve as a tool to extract the individual tidal deformabilities, but this is made difficult by degeneracies between them in the gravitational wave model. We here resolve this problem by discovering approximately universal relations between dimensionless combinations of the individual tidal deformabilities. We show that these relations break degeneracies in the gravitational wave model, allowing for the accurate extraction of both deformabilities. Such measurements can be used to better differentiate between equation-of-state models, and improve tests of General Relativity and cosmology.