Neutron star cooling with a dynamic stellar structure

TL;DR

This paper extends neutron star cooling theory to include dynamic structural changes during cooling, finding that the static approximation remains valid as dynamic effects slightly accelerate cooling.

Contribution

It introduces a dynamic model of neutron star structure evolution during cooling, improving the understanding of thermal evolution processes.

Findings

Dynamic effects slightly accelerate neutron star cooling.

Static approximation remains valid for practical calculations.

Cooling energy estimates are marginally lower with dynamic modeling.

Abstract

The observations combined with theory of neutron star (NS) cooling play a crucial role in achieving the intriguing information of the stellar interior, such as the equation of state (EOS), composition and superfluidity of dense matter. The traditional NS cooling theory is based on the assumption that the stellar structure does not change with time. The validity of such a static description has not yet been confirmed. We generalize the theory to a dynamic treatment; that is, continuous change of the NS structure (rearrangement of the stellar density distribution with the total baryon number fixed) as the decrease of temperature during the thermal evolution, is taken into account. It is found that the practical thermal energy used for the cooling is slightly lower than that is estimated in static situation, and hence the cooling of NSs is accelerated correspondingly but the effect is rather weak. Therefore, the static treatment is a good approximation in the calculations of NS cooling.