Combustion adiabat and the maximum mass of a quark star

TL;DR

This paper uses the combustion adiabat equation to analyze the phase transition from neutron stars to quark stars, revealing a maximum mass limit and suggesting that such transitions may not always originate from the star's center.

Contribution

It introduces a method to determine the maximum mass of quark stars via the combustion adiabat and explores the feasibility of phase transitions in neutron stars.

Findings

Maximum quark pressure indicates a maximum mass limit for quark stars.

Phase transition from neutron to quark star may not always start at the star's center.

Most transitions likely occur via slow deflagration at low and intermediate densities.

Abstract

We solve the Combustion adiabat (CA) or the Chapman-Jouget adiabat equation to study the phase transition (PT) of a neutron star (NS) to a quark star (QS). The hadronic matter and quark matter equation of states are used to calculate the matter velocities on either side of the shock front. The CA with the hadronic matter as an input is solved to obtain the corresponding quark matter values. The maximum of the quark pressure is reflected in the retracing of the path in the CA curve. The downstream quark pressure maximum implies towards a maximum mass limit of a phase transformed QS which is different from the regular mass limit of an ordinary QS. Further, the characterization of velocities suggest that the PT from NS to QS is not always feasible from the center of the star. The possible mode of combustion in NSs is likely to be a slow deflagration in most of the low and intermediate density range. The result is crucial and emphasizes on the fact that PT in NSs does not always starts from the center and sometimes a NS does not suffers a PT at all.