Non-local quark models for description of dense matter in the cores of neutron stars

TL;DR

This thesis investigates the potential presence of quark matter in neutron star cores using advanced models, phase transition formalisms, and compares theoretical predictions with astrophysical observations.

Contribution

It introduces a comprehensive analysis of quark matter phases in neutron stars using nonlocal NJL models and different phase transition formalisms, enhancing understanding of dense matter.

Findings

Quark matter presence in neutron stars remains plausible.

Phase diagrams and equations of state are developed for finite temperature.

Results align with recent astrophysical observations.

Abstract

This thesis work focuses on studying the possible existence of phase transitions in the immediate compact remnants of core collapse supernova, neutron stars, and the theoretical models that describe the interior of dense matter. Specifically, we are interested in analyzing the feasibility of a transition from hadronic matter to quark matter in the cores of these objects. For the phase transition we will use two different formalisms: the Maxwell formalism or abrupt phase transition and the Gibbs formalisms or mixed phase transition. For the description of hadronic matter, we will use different parametrizations of the relativistic mean field model with density-dependent coupling constants. For the description of quark matter we will use an effective nonlocal Nambu Jona-Lasinio model of three flavors with vector interactions, in which we will include the possibility of formation of diquarks to model a superconducting phase of color in $SU(3)$. Phase diagrams and equations of state of quark matter at finite temperature are presented, and the influence of that type of matter on observables associated with neutron stars is investigated. The simplified thermal evolution of compact stars during their formation is studied, from their state of proto-neutron stars to that of cold neutron stars, and the results obtained are compared with recent astrophysical observations. The results obtained indicate that the occurrence of quark matter in the nuclei of these stars remains a promising possibility. The fact that the use of more realistic models for the description of the dense matter in these objects indicates the presence of quark matter inside neutron stars, could be an answer to the question of the behavior of that kind of matter and the determination of its corresponding equation of state.