On the Cooling of the Neutron Star in Cassiopeia A

TL;DR

This paper explains the observed cooling of the neutron star in Cassiopeia A using a nuclear medium cooling model that accounts for medium effects and predicts future observations could reveal fast cooling processes.

Contribution

It introduces a comprehensive nuclear medium cooling scenario that successfully explains the neutron star's cooling data, emphasizing medium modifications and reduced thermal conductivity.

Findings

Cooling data explained by medium-modified processes

Thermal conductivity significantly suppressed by medium effects

Future observations may confirm fast cooling mechanisms

Abstract

We demonstrate that the high-quality cooling data observed for the young neutron star in the supernova remnant Cassiopeia A over the past 10 years--as well as all other reliably known temperature data of neutron stars--can be comfortably explained within the "nuclear medium cooling" scenario. The cooling rates of this scenario account for medium-modified one-pion exchange in dense matter and polarization effects in the pair-breaking formations of superfluid neutrons and protons. Crucial for the successful description of the observed data is a substantial reduction of the thermal conductivity, resulting from a suppression of both the electron and nucleon contributions to it by medium effects. We also find that possibly in as little as about ten years of continued observation, the data may tell whether or not fast cooling processes are active in this neutron star.