Probing internal dissipative processes of neutron stars with gravitational waves during the inspiral III: Implications from GW170817

The gravitational waves emitted by neutron star binaries provide a unique window into 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 can leave a measurable imprint on the phase of the gravitational waves emitted. In this talk, I will present our results on the first constraint on the dissipative tidal deformability of a neutron star from the GW170817 (binary neutron star) event detected by LIGO and Virgo. From this constraint, we obtain an order of magnitude bound on the averaged bulk and shear viscosity of each star during the inspiral. Further, using inspiral data from future GW170817-like events, we forecast the measurability of the averaged shear and bulk viscosities during the fifth observing run of advanced LIGO and Virgo, and with third-generation detectors, like Cosmic Explorer. Our constraints on the averaged bulk and shear viscosities 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.