Probing the equation of state of neutron star matter with gravitational waves from binary inspirals in light of GW170817: a brief review

TL;DR

This review discusses how gravitational waves from neutron star mergers, especially GW170817, provide insights into the dense matter equation of state through tidal deformability measurements, highlighting recent constraints and future prospects.

Contribution

It summarizes the role of tidal effects in gravitational wave signals and reviews the first constraints on neutron star matter from GW170817 data, outlining future research directions.

Findings

GW170817 provided the first constraints on tidal deformability.

Tidal effects encode information about the neutron star equation of state.

Future GW observations will improve understanding of dense matter physics.

Abstract

Neutron stars are unique testbeds for exploring the physics of strongly interacting matter in extreme regimes of density, temperature, and isospin that are not accessible anywhere else in the universe. The nature of neutron star matter can now be probed with gravitational-waves (GWs) from binary driven by nonlinear gravity, where phenomena such as tidal effects lead to characteristic matter-dependent GW signatures. We focus here on the dominant tidal GW imprints that were most relevant for the event GW170817. We review the role of the tidal deformability parameter, its definition, computation, and relation to the equation of state. We briefly discuss the implications of GW170817, representing the first-ever constraints on tidal deformability from GW data. Finally, we outline opportunities and challenges for probing subatomic physics with GWs, as the measurements will become more precise and will probe a diversity of the binary neutron star population in the coming years.