General relativistic shocks in connection with neutron stars

TL;DR

This paper investigates general relativistic shocks in neutron stars, deriving jump conditions and applying them to model combustion fronts that convert neutron star matter into quark matter, revealing potential super-luminous velocities.

Contribution

It introduces new derivations of shock jump conditions in general relativity and applies them to neutron star combustion, showing possible super-luminous shock velocities.

Findings

Matter velocities can exceed the speed of light in certain conditions.

Space-like shocks likely correspond to deflagration processes.

Time-like shocks can be detonations with super-luminous velocities.

Abstract

Astrophysical shocks are very common and are interesting as they are responsible for particle acceleration in supernovas, blazers, and neutron stars. In this work, we study general relativistic shocks from the frame of the front. We derive the jump conditions and the Taub adiabat equation for both the space-like and time-like shocks. We solve these equations in a neutron star system where the shock is followed by a combustion front which is deconfining hadronic matter to quark matter. The maximum mass of the daughter quark star (generated from the combustion of the parent neutron star) is consistent with the maximum mass limit for the EoS sequence. We find that matter velocities for GR shocks under suitable conditions can break the speed of light limit indicating a very fast combustion process. Also, the matter velocities imply that for space-like shocks the combustion process is most probably a deflagration and for time-like shocks, it is a detonation and can even proceed with velocities that are super-luminous.