First constraint on the dissipative tidal deformability of neutron stars

TL;DR

This paper presents the first observational constraint on the dissipative tidal deformability of neutron stars using GW data from GW170817, providing bounds on internal viscosities and prospects for future improvements with advanced detectors.

Contribution

It introduces the first constraint on neutron star dissipative tidal deformability from gravitational wave observations, linking GW data to internal viscosity parameters.

Findings

Established upper bounds on bulk and shear viscosity during inspiral

Forecasted two orders of magnitude improvement with third-generation detectors

Provided insights into neutron star internal physics and nuclear matter models

Abstract

The gravitational waves (GWs) emitted by neutron star binaries probe the physics of matter at supra nuclear densities. During the late inspiral, tidal deformations raised on each star by the gravitational field of its companion depend crucially on the star's internal properties. The misalignment of a star's tidal bulge with its companion's gravitational field encodes the strength of internal dissipative processes, which imprint onto the phase of the gravitational waves emitted. We here analyze GW data from the GW170817 (binary neutron star) event detected by LIGO and Virgo and find the first constraint on the dissipative tidal deformability of a neutron star. From this constraint, \emph{assuming} a temperature profile for each star in the binary, we obtain an order of magnitude bound on the averaged bulk ($\zeta$) and shear ($\eta$) viscosity of each star during the inspiral.: $\zeta \lesssim 10^{31} \mathrm{g}\;\mathrm{cm}^{-1}\mathrm{s}^{-1}$ and $\eta \lesssim 10^{28} \mathrm{g}\;\mathrm{cm}^{-1}\mathrm{s}^{-1} $. We forecast that these bounds could be improved by two orders of magnitude with third-generation detectors, like Cosmic Explorer, using inspiral data. These constraints already inform nuclear physics models and motivate further theoretical work to better understand the interplay between viscosity and temperature in the late inspiral of neutron stars.