Revealing Phase Transition in Dense Matter with Gravitational Wave Spectroscopy of Binary Neutron Star Mergers

We use numerical relativity simulations of binary neutron star mergers to show that high density deconfinement phase transitions (PTs) to quark matter can be probed using multimodal postmerger gravitational wave (GW) spectroscopy. Hadron-quark PTs suppress the one-armed spiral instability in the remnant. This is manifested in an anti-correlation between the energy carried in the $l=2,m=1$ GW mode and energy density gap which separates the two phases. Consequently, a single measurement of the signal-to-noise ratios of the $l=2,m=1$ and $l=2,m=2$ GW modes could constrain the energy density gap of the PT.