Probing internal dissipative processes of neutron stars with gravitational waves during the inspiral

A long-standing goal in astrophysics and nuclear particle physics has been to determine the neutron star equation of state, i.e., the relation between the pressure and the energy density in the interior of a neutron star. We find that modeling internal dissipative effects in neutron stars binaries during the inspiral requires that one introduce a new tidal deformability parameter--the dissipative tidal deformability. We show that (as is the case for black holes) the dissipative tidal deformability corrects the gravitational-wave phase at 4 post-Newtonian order for quasi-circular binaries. This correction receives a large finite-size enhancement by the stellar compactness, analogous to the case of the tidal deformability, which makes the parameter potentially measurable with ground-based gravitational wave detectors. The correction is not degenerate with the time of coalescence, which also enters at 4PN order, because it contains a logarithmic frequency-dependent contribution that breaks the partially correlations. We briefly discuss our derivation of this result, our ongoing work on computing and measuring the dissipative tidal deformability of neutron stars.