Speaker
Description
The convergence of multi-messenger observations—NICER, GW170817, and theoretical calculations—has tightly constrained the neutron star equation of state, pointing to a non-monotonic sound speed that suggests possible quark matter in massive neutron star cores. However, the masquerade effect obscures the nature of this transition in static stars.
I will show how binary neutron star mergers provide a dynamical probe of this transition. Using general-relativistic simulations with a quark-hadron crossover equation of state, we find the post-merger remnant is less compact than in purely hadronic models, producing a lower, more stable gravitational-wave frequency f2. This signature clearly differs from the rapid frequency evolution expected from a strong first-order phase transition and may be detectable by next-generation observatories.
Our results show that post-merger gravitational-wave spectra can discriminate between hadron-quark transition mechanisms, complementing constraints from static neutron star properties.