Numerical Simulation of the Hydrodynamical Combustion to Strange Quark Matter

TL;DR

This paper presents a numerical simulation of neutron matter burning into strange quark matter inside neutron stars, revealing faster laminar front speeds and the impact of neutrino cooling on the conversion process.

Contribution

It introduces a comprehensive 1D hydrodynamical model including neutrino emission and strange quark diffusion, providing new insights into the burning front dynamics in neutron stars.

Findings

Burning front speeds are 0.002-0.04 times the speed of light.

Neutrino cooling causes the front to stall at lower densities.

Analytic solutions agree with numerical results for fluid velocities.

Abstract

We present results from a numerical solution to the burning of neutron matter inside a cold neutron star into stable (u,d,s) quark matter. Our method solves hydrodynamical flow equations in 1D with neutrino emission from weak equilibrating reactions, and strange quark diffusion across the burning front. We also include entropy change due to heat released in forming the stable quark phase. Our numerical results suggest burning front laminar speeds of 0.002-0.04 times the speed of light, much faster than previous estimates derived using only a reactive-diffusive description. Analytic solutions to hydrodynamical jump conditions with a temperature dependent equation of state agree very well with our numerical findings for fluid velocities. The most important effect of neutrino cooling is that the conversion front stalls at lower density (below approximately 2 times saturation density). In a 2-dimensional setting, such rapid speeds and neutrino cooling may allow for a flame wrinkle instability to develop, possibly leading to detonation.