Detectability of finite-temperature effects from neutron star mergers with next-generation gravitational wave detectors

Observations of the high-frequency gravitational waves (GWs) emitted by the hot and massive remnant of a binary neutron star merger will provide new probes of the dense-matter equation of state (EOS). We show that current uncertainties in the thermal physics can cause the emergent GW spectum to differ by a degree comparable to changing the cold EOS by ±~120 m in the characteristic radius of a neutron star. Unless a very close binary neutron star merger takes place, these effects are unlikely to be measurable with current GW detectors. However, with proposed next-generation detectors such as Cosmic Explorer or Einstein Telescope, the effects can be distinguished for events at distances of up to ~80--200 Mpc, if the cold EOS is sufficiently well constrained.