Phase transition in compact stars: nucleation mechanism and γ-ray bursts revisited

Abstract

We have revisited the nucleation process based on the Lifshitz-Kagan theory, which is the underlying mechanism of conversion of a pulsar constituted of hadronic matter to a quark star. We have selected appropriate models that have been tested against experimental and observational constraints to restrict the model arbitrariness present in previous investigations. The phase transition pressures and chemical potentials have been identified and afterwards, the tunneling probabilities and the nucleation time were computed. The critical pressures for which the half life of the metastable hadronic phase is one year were obtained. Even with the restrictions imposed to the selection of models, the results remained model dependent, but we found that the tunneling that makes possible the appearance of stable matter requires an overpressure that is practically independent of the quark matter bag constant. Finally, we have confirmed that the nucleation process can be one of the causes of gamma-ray bursts.

On the nature of the mass-gap object in the GW190814 event

“…If we want to construct a hybrid star, we have to ensure that the u − d − s matter (as well, the u − d matter) is unstable. Otherwise, it is possible that, as soon as the core of the star converts to the quark phase, the entire star converts into a quark star in a finite amount of time [27,28].…”

A Strange Star Scenario for the Formation of Eccentric Millisecond Pulsar/Helium White Dwarf Binaries

“…The difference between the gravitational masses of NS and SS with the same baryon number is also widely studied (Bombaci & Datta 2000;Drago et al 2007;Marquez & Menezes 2017). It is generally thought ∆M = M NS − M SS ≈ 0.15 M for NS with a mass of M NS 1.5 M 1 , i. e. the mass loss ratio ∆M/M NS during PT is about 10%.…”

Hadron-quark phase transition: the QCD phase diagram and stellar conversion

“…This is the first condition that enables the conversion of a metastable neutron star into a quark or hybrid star. The other condition is that the gravitational mass of the initial metastable hadronic star must be bigger than the gravitational mass of the final star, either quark or hybrid star, for a given baryonic mass, so that the conversion can be exothermal in rest while respecting the baryonic number conservation [21]. In Figure 7 we ilustrate the results by plotting the ratio between the gravitational and baryonic masses with respect to the baryonic mass, in a way that highlights the small differences between the curves while preserving the interpretation that the conversion is energetically allowed only if the final configuration is below the initial one for M B fixed.…”

“…The models to be used here are all included in the Nambu-Jona-Lasinio (NJL) model framework [3] in order to naturally describe the chiral characteristics of QCD matter. The two EoS model has been applied to the study of the hadron-quark phase transition in several studies, [18,[21][22][23][24][25]. In particular, in [24] the effect of the vector contribution in the quark-matter description was considered.…”