General-purpose equations of state for hadron-quark matter: first application to accretion-induced phase transitions in neutron stars

Abstract

Strong first-order phase transitions in the cores of neutron stars (NSs) can have profound implications for astrophysical observables, however, their existence remains an open question. Since most NSs form in binary systems, they are expected to experience prolonged episodes of mass accretion that gradually increase their central density and can potentially trigger such a transition. This might, in turn, generate observable multi-messenger signals, as suggested by previous studies. Motivated by this prospect, we generate a new set of equations of state for hadron--quark matter with first-order phase transitions of various strengths, including neutrino absorption opacities in the quark phase as well. We then perform general-relativistic radiation hydrodynamics simulations of NSs undergoing accretion-induced phase transitions. In contrast to previous findings, our results indicate that these systems do not produce unbound ejecta for the models considered, making accretion-induced phase transitions unlikely sources of observable electromagnetic transients. However, we find that transitions are accompanied by intense neutrino emission, with peak luminosities reaching $\sim10^{52}~\mathrm{erg/s}$ for the strongest transition considered. To facilitate future numerical studies, we make the family of equations of state and neutrino opacities used in this work publicly available, enabling the systematic exploration of the role of the phase transition strength.