Nuclear medium cooling scenario in the light of new Cas A cooling data and the 2 M_sun pulsar mass measurements

TL;DR

This paper demonstrates that the nuclear medium cooling scenario, incorporating medium effects on neutrino emission and thermal conductivity, can successfully explain neutron star cooling data, including recent Cassiopeia A observations and high-mass pulsar measurements.

Contribution

It introduces a comprehensive nuclear medium cooling model that accounts for recent observational data and high-mass neutron stars, enhancing previous cooling theories.

Findings

Successfully explains Cassiopeia A cooling data

Reproduces observed neutron star masses up to 2.1 solar masses

Highlights the importance of medium-modified thermal conductivity

Abstract

Recently, Elshamounty et al. performed a reanalysis of the surface temperature of the neutron star in the supernova remnant Cassiopeia A on the basis of Chandra data measured during last decade, and added a new data point. We show that all reliably known temperature data of neutron stars including those belonging to Cassiopea A can be comfortably explained in our "nuclear medium cooling" scenario of neutron stars. The cooling rates account for medium-modified one-pion exchange in dense matter, polarization effects in the pair-breaking-formation processes operating on superfluid neutrons and protons paired in the 1S_0 state, and other relevant processes. The emissivity of the pair-breaking-formation process in the 3P_2 state is a tiny quantity within our scenario. Crucial for a successful description of the Cassiopeia A cooling proves to be the thermal conductivity from both, the electrons and nucleons, being reduced by medium effects. Moreover, we exploit an EoS which stiffens at high densities due to an excluded volume effect and is capable of describing a maximum mass of 2.1 M_sun, thus including the recent measurements of PSR J1614-2230 and PSR J0348+0432.