Speaker
Description
During the late stages of a neutron star binary inspiral finite-size effects come into play, with the tidal deformability of the supranuclear density matter leaving an imprint on the gravitational-wave signal. As demonstrated in the case of GW170817—the first direct detection of gravitational waves from a neutron star binary—this can lead to constraints on the neutron star equation of state. As detectors become more sensitive, the hydrostatic response of the neutron star to the tidal field of its companion (equilibrium tide) needs to be supplemented by dynamical effects, such as oscillation mode resonances triggered by the orbital motion (dynamical tide). We calculate the contribution of the various stellar oscillation modes to the tidal deformability and demonstrate the (anticipated) dominance of the fundamental mode. We show what the impact of the matter composition is on the tidal deformability, as well as the changes induced by more realistic additions to the problem, e.g. the presence of an elastic crust, superfluidity, and rotation. Finally, based on this formulation, we develop a simple phenomenological model describing the effective tidal deformability of neutron stars and show that it provides a surprisingly accurate representation of the dynamical tide close to merger.
