Cooling of the neutron star in Cassiopeia A

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. In a few more decades of continued monitoring of Cassiopeia A, the observed data may allow one to put additional constraints on the efficiency of different cooling processes in neutron stars.