Neutron star mergers as a probe of the quark matter equation of state

We perform the first simulations of binary neutron-star mergers which adopt various parameterizations of the quark-hadron crossover (QHC) equation of state (EOS). These are constructed from combinations of a hardronic EOS (up tp 2 times the nuclear satuation density) and a quark-matter EOS (2-5 times the saturation density). At the crossover densities the QHC EOSs have a gradually increasing stiffness approaching the stiffness of the strongly correlated quark matter. This enhanced stiffness leads to significantly longer lifetimes of the hypermassive neutron star than that for a pure hadronic EOS. We find a dual nature of these EOSs such that their maximum chirp gravitational wave frequencies fall into the category of a soft EOS while the dominant peak frequencies of the postmerger stage falls in between that of a soft and stiff hadronic EOS. An observation of this kind of dual nature in the characteristic gravitational wave frequencies will provide crucial evidence for the existence of strongly interacting quark matter at the crossover densities.