Rogue waves and standard sirens: Physics and Astrophysics from binary neutron star merge (Special DTP Colloquium)

Advanced gravitational wave (GW) detectors like LIGO and VIRGO routinely detect signals from merging compact binaries. While most detections are from binary black holes, signals from binary neutron star (BNS) systems contain additional valuable information. In BNS systems, neutron stars deform within each other’s tidal potential, leaving a distinct imprint on the GW signal. Measuring this imprint provides insights into the equation of state of dense matter above the nuclear saturation density. BNS mergers also produce transient electromagnetic bursts, enabling simultaneous measurement of their redshift and distance, which is valuable for cosmological studies. I'll discuss our recent work on two aspects of BNS systems: First, we developed a model of tidal deformations in neutron star binaries that accounts for the anharmonic nature of internal oscillations in the stars. This model may resolve discrepancies between GW signals from simple analytical calculations and numerical simulations. It also predicts that buoyancy waves are resonantly excited to large amplitudes during the inspiral phase, leaving a novel imprint of the stars' density and composition on the GW signal. Second, I will introduce methods to quickly and accurately constrain binary parameters from GW signals using modest computing resources, facilitating rapid follow-up observations and large-scale studies of BNS populations.