Relativistic Mass Ejecta from Phase-transition-induced Collapse of Neutron Stars

TL;DR

This paper models the collapse of neutron stars induced by phase transitions, revealing pulsating neutrino emissions that can eject relativistic mass layers, potentially explaining gamma-ray bursts.

Contribution

It introduces a 3D hydrodynamic simulation of phase-transition-induced neutron star collapse, highlighting neutrino oscillations and relativistic ejecta as a novel mechanism.

Findings

Neutrinos oscillate with acoustic frequency, out of phase with temperature and density.

Pulsating neutrino fluxes significantly enhance pair creation and mass ejection.

Ejected mass can reach relativistic speeds, possibly linked to gamma-ray bursts.

Abstract

We study the dynamical evolution of a phase-transition-induced collapse neutron star to a hybrid star, which consists of a mixture of hadronic matter and strange quark matter. The collapse is triggered by a sudden change of equation of state, which result in a large amplitude stellar oscillation. The evolution of the system is simulated by using a 3D Newtonian hydrodynamic code with a high resolution shock capture scheme. We find that both the temperature and the density at the neutrinosphere are oscillating with acoustic frequency. However, they are nearly 180$^{\circ}$ out of phase. Consequently, extremely intense, pulsating neutrino/antineutrino fluxes will be emitted periodically. Since the energy and density of neutrinos at the peaks of the pulsating fluxes are much higher than the non-oscillating case, the electron/positron pair creation rate can be enhanced dramatically. Some mass layers on the stellar surface can be ejected by absorbing energy of neutrinos and pairs. These mass ejecta can be further accelerated to relativistic speeds by absorbing electron/positron pairs, created by the neutrino and antineutrino annihilation outside the stellar surface. The possible connection between this process and the cosmological Gamma-ray Bursts is discussed.