http://arxiv.org/abs/2210.14048
It is currently unknown if neutron stars are composed of nucleons only or are hybrid stars, i.e., in addition to nucleonic crusts and outer cores, they also possess quark cores. Quantum chromodynamics allows for such a phase transition possibility, but accurate calculations in the range of interest for compact stars are still elusive. Here we investigate some crust-breaking aspects of hybrid stars. We show that the crust-breaking orbital/gravitational wave frequency and maximum ellipticity are sensitive to the quark-hadron density jump and equation of state stiffness. Remarkably, the crust-breaking frequency related to static tides scales linearly with the mass of the star (for a given companion’s mass), and its slope encompasses information about the microphysics of the star. When a liquid quark core touches an elastic hadronic phase, which could be the result of a significant energy-density jump, the maximum ellipticity can increase orders of magnitude when compared to the case the liquid quark core touches a liquid hadronic phase, such as the outer core. Our analysis also suggests that a given upper limit to the ellipticity or a crust-breaking frequency could have representatives in stars with either small or very large energy-density jumps. Therefore, upper limits to the ellipticity from continuous gravitational wave observations of the LIGO-Virgo-KAGRA network for isolated stars, and gamma-ray precursors associated with crust breaking in inspiraling binary systems may constrain some aspects of phase transitions in neutron stars.
J. Pereira, M. Bejger, P. Haensel, et. al.
Wed, 26 Oct 22
27/73
Comments: 10 pages, 6 figures. Comments welcome