Abstract
We study in detail the nuclear aspects of a neutron-star merger in which deconfinement to quark matter takes place. For this purpose, we make use of the Chiral Mean Field (CMF) model, an effective relativistic model that includes self-consistent chiral symmetry restoration and deconfinement to quark matter and, for this reason, predicts the existence of different degrees of freedom depending on the local density/chemical potential and temperature. We then use the out-of-chemical-equilibrium finite-temperature CMF equation of state in full general-relativistic simulations to analyze which regions of different QCD phase diagrams are probed and which conditions, such as strangeness and entropy, are generated when a strong first-order phase transition appears. We also investigate the amount of electrons present in different stages of the merger and discuss how far from chemical equilibrium they can be and, finally, draw some comparisons with matter created in supernova explosions and heavy-ion collisions.
Highlights
The interior of neutron stars covers an incredible range of densities going from about 104 g/cm3 in the crust to about 1015 g/cm3 in the core, corresponding to several times the nuclear saturation density [1]
In the absence of a fundamental theory that can be applied in the whole energy regime and conditions necessary for our study, we make use of an effective model, the Chiral Mean Field (CMF) model, which is based on a nonlinear realization of the SU(3) chiral sigma formalism [18]
We start by analyzing the evolution of the densest and hottest parts of the hypermassive neutron star (HMNS) in the left panel of Fig. 1, which reports the regions of the standard QCD phase diagram that are probed in our neutron-star merger simulation
Summary
The interior of neutron stars covers an incredible range of densities going from about 104 g/cm in the crust to about 1015 g/cm in the core, corresponding to several times the nuclear saturation density [1]. [2,3] for some recent reviews) Such extreme densities combined with temperatures of several tens of MeV are relevant if the equation of state (EOS). [8,9] that hyperons can modify the frequency and amplitude of gravitational waves emitted by neutron-star mergers. These changes are expected to be visible even before the merger takes place, as hyperons are usually triggered at intermediate densities, specially when temperature effects are pronounced. The complex dynamics found in these works, as well as the impact on the electromagnetic counterpart to be expected from this process [16], clearly calls for more extended and detailed work
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