Mass-radius constraints for the neutron star EoS - Bayesian analysis

TL;DR

This paper introduces a Bayesian analysis method using mass-radius constraints to determine the neutron star equation of state, highlighting the potential to identify a first order phase transition and a critical endpoint in the QCD phase diagram.

Contribution

It presents a novel Bayesian approach with disjunct M-R constraints to infer the EoS and assess the nature of the deconfinement transition in neutron stars.

Findings

A radius gap of about 3 km suggests a strong first order phase transition.

The analysis supports the existence of a critical endpoint in the QCD phase diagram.

Radius measurements can distinguish between crossover and first order transitions.

Abstract

We suggest a new Bayesian analysis (BA) using disjunct M-R constraints for extracting probability measures for cold, dense matter equations of state (EoS). One of the key issues of such an analysis is the question of a deconfinement transition in compact stars and whether it proceeds as a crossover or rather as a first order transition. We show by postulating results of not yet existing radius measurements for the known pulsars with a mass of $2M_\odot$ that a radius gap of about 3 km would clearly select an EoS with a strong first order phase transition as the most probably one. This would support the existence of a critical endpoint in the QCD phase diagram under scrutiny in present and upcoming heavy-ion collision experiments.