Modelindependent constraints on superfluidity from the cooling neutron star in Cassiopeia A
Abstract
We present a new modelindependent (applicable for a broad range of equations of state) analysis of the neutrino emissivity due to triplet neutron pairing in neutron star cores. We find that the integrated neutrino luminosity of the Cooper Pair Formation (CPF) process can be written as a product of two factors. The first factor depends on the neutron star mass, radius, and maximal critical temperature of neutron pairing in the core, T_{Cnmax}, but not on the particular superfluidity model; it can be expressed by an analytical formula valid for many nucleon equations of state. The second factor depends on the shape of the critical temperature profile within the star, the ratio of the temperature T to T_{Cnmax}, but not on the maximal critical temperature itself. While this second factor depends on the superfluidity model, it obeys several modelindependent constraints. This property allows one to analyse the thermal evolution of neutron stars with superfluid cores without relying on a specific model of their interiors. The constructed expressions allow us to perform a selfconsistent analysis of spectral data and neutron star cooling theory. We apply these findings to the cooling neutron star in the Cassiopeia A supernova remnant using 14 sets of observations taken over 19 yr. We constrain T_{Cnmax} to the range of (510) × 10^{8} K. This value depends weakly on the equation of state and superfluidity model, and will not change much if cooling is slower than what the current data suggest. We also constrain the overall efficiency of the CPF neutrino luminosity.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 September 2021
 DOI:
 10.1093/mnras/stab1695
 arXiv:
 arXiv:2106.05692
 Bibcode:
 2021MNRAS.506..709S
 Keywords:

 dense matter;
 neutrinos;
 stars: neutron;
 supernovae: individual: Cassiopeia A;
 Xrays: stars;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 18 pages, 14 figures, 6 tables