Speaker
Description
Multi-messenger observations—from NICER radius measurements and GW170817 tidal constraints to theoretical bounds from chiral EFT and perturbative QCD—have significantly narrowed the space of neutron star equation of state (EOS). These advances increasingly favor a non-monotonic sound speed, hinting at exotic phases like quark matter in massive neutron star cores. However, due to the "masquerade effect," static properties alone struggle to distinguish between a smooth crossover and a sharp phase transition.
In this talk, I will discuss how binary neutron star mergers may serve as a dynamical probe of this transition. Using general-relativistic simulations with a quark-hadron crossover EOS, we find that the post-merger remnant is systematically less compact than in purely hadronic models, producing a lower peak gravitational-wave frequency, f2. This signature differs from that in strong first-order phase transitions. Our results suggest that post-merger gravitational-wave signals could help distinguish between different high-density transition scenarios, serving as a complement to static neutron star measurements.
