  We study the impact of finite-temperature effects in numerical-relativity
simulations of binary neutron star mergers with microphysical equations of
state and neutrino transport in which we vary the effective nucleon masses in a
controlled way. We find that, as the specific heat is increased, the merger
remnants become colder and more compact due to the reduced thermal pressure
support. Using a full Bayesian analysis, we demonstrate that this effect will
be measurable in the postmerger gravitational wave signal with next-generation
observatories at signal-to-noise ratios of 15.
