Institute for Advanced Study Astrophysics Seminar

Merging binary neutron stars are an important class of sources for advanced gravitational wave (GW) detectors such as LIGO and VIRGO, as well as for searches for transient astronomical events. In this talk, I will discuss two aspects of the GW signals from these systems, that are crucial for extracting astrophysical insights from detections. 

The first aspect is the effect of the components’ tidal deformations on a binary’s orbital dynamics, and their impact on the detected GW signal. Typically, models of the effect start from the picture that the tidal deformations are each neutron star's linear response to the companion’s tidal field. However, the implied change to the signal’s phase is off by around a radian near the merger, when compared to numerical simulations of the mergers. I will show that this extra phase originates in the anharmonicity of the neutron stars’ fundamental modes of oscillation.

The second aspect is the inference of a binary’ parameters from the detected signal, which is a crucial step both for its interpretation as well as for electromagnetic followup efforts. The inference can be time-consuming, and approximate initial sky-maps can significantly depart from the final results. I will introduce methods we developed to rapidly and accurately derive constraints on the binary’s parameters, that only require modest computing resources.