Analyzing Neutron Star in HESS J1731-347 from Thermal Emission and Cooling Theory

TL;DR

This paper models the thermal emission and cooling behavior of the neutron star in HESS J1731-347, providing new constraints on its mass and radius by combining spectral data with advanced cooling theory.

Contribution

It introduces an improved cooling model accounting for neutrino emission from neutron-neutron collisions, refining neutron star parameter estimates.

Findings

Neutron star's mass and radius constraints are more precise.

Strong proton superfluidity and carbon envelope explain observed heat.

Neutrino emission from neutron-neutron collisions significantly affects cooling.

Abstract

The central compact object in the supernova remnant HESS J1731-347 appears to be the hottest observed isolated cooling neutron star. The cooling theory of neutron stars enables one to explain observations of this star by assuming the presence of strong proton superfluidity in the stellar core and the existence of the surface heat blanketing envelope which almost fully consists of carbon. The cooling model of this star is elaborated to take proper account of the neutrino emission due to neutron-neutron collisions which is not suppressed by proton superfluidity. Using the results of spectral fits of observed thermal spectra for the distance of 3.2 kpc and the cooling theory for the neutron star of age 27 kyr, new constraints on the stellar mass and radius are obtained which are more stringent than those derived from the spectral fits alone.