Gravity seminar - Patricia Schmidt Seminar

Abstract: Gravitational waves (GWs) from colliding neutron star binaries provide a unique means to probe matter and fundamental physics at supranuclear densities. Whilst adiabatic tidal effects related to the tidal deformability of the star leave the strongest imprint in the gravitational-wave signal, additional dynamical tidal effects due to fundamental oscillation modes (f-modes) arise at late times in the binary inspiral, modifying the GW phase at high frequencies. In General Relativity, the tidal deformability and the f-mode frequency are tied to each other through quasi-universal relations – this may not be true in alternative theories of gravity or for exotic compact objects. Thus, extracting information not only on the tidal deformability but also on the frequencies of fundamental modes has the potential to enable novel tests of GR and matter at the extreme. I will first present a new approximate closed-form model for the GW phase from dynamical tides for circular, nonspinning compact binaries. This additional tidal phase depends explicitly on the f-mode frequency of each compact object, making f-mode asteroseismology an accessible observable with GW detections of the inspiral phase. I will then show that without invoking universal relations, we can place a lower limit on the f-mode frequency for current GW observations. In a re-analysis of GW170817, we estimate a lower limit on the f-mode frequency consistent with the predictions from universal relations. Finally, I will present prospects for measuring the f-mode frequency from inspiraling neutron star binaries with future GW observatories.