Thermalization time and specific heat of the neutron stars crust

Abstract

We discuss the thermalization process of the neutron star's crust described by solving the heat-transport equation with a microscopic input for the specific heat of baryonic matter. The heat equation is solved with initial conditions specific to a rapid cooling of the core. To calculate the specific heat of inner-crust baryonic matter, that is, nuclear clusters and unbound neutrons, we use the quasiparticle spectrum provided by the Hartree-Fock-Bogoliubov approach at finite temperature. In this framework, we analyze the dependence of the crust thermalization on pairing properties and on cluster structure of inner-crust matter. It is shown that the pairing correlations reduce the crust thermalization time by a large fraction. The calculations show also that the nuclear clusters have a non-negligible influence on the time evolution of the surface temperature of the neutron sta

Low-energy collective excitations in the neutron star inner crust

“…This neutron contribution is enormous and will always dominate in the layers where neutrons are normal. Once superfluidity sets in, however, C n V is strongly suppresssed and becomes negligible when the temperature is much lower than the critical temperature T n c [23,24]. Given the density dependence of the neutron 1 S 0 gap there are only two regions, just above the neutron drip point and possibly in the deepest part of the crust, where C n V is relevant (see, e.g., Ref.…”

“…While the existence of two weakly damped longitudinal modes is unique to the superfluid phase, entrainment is fairly insensitive to superfluidity provided the pairing gap ∆ ≪ µ n [21], which is the case in most of the inner crust [22][23][24].…”

Thermonuclear fusion in dense stars

“…The cooling rate cool depends on the first and second derivatives of the temperature, therefore the condition (24) is not local, but depends on the overall temperature and density structure of the envelope. Thermal relaxation of the neutron star crust occurs on the scale of a few tens of years, while the relaxation time of the outer envelopes is still shorter (Lattimer et al 1994;Gnedin et al 2001;Fortin et al 2010). Therefore, the outer envelopes are considered quasistationary for most of the astrophysical problems, and their thermal structure is calculated at stationary equilibrium (Gudmundsson et al 1983).…”

Superfluid properties of the inner crust of neutron stars

“…The pairing interaction matrix elements are computed at first order only, leaving higher-order correlations for future investigations. For comparison, we also perform calculations with effective pairing interactions, namely the Gogny D1 interaction [15] and a density-dependent delta interaction (DDDI) [16], which have both been used in the past as pairing interactions in WS calculations [17][18][19][20][21]. The superfluid properties obtained with these effective pairing forces turn out to differ substantially from those obtained with realistic pairing potentials (see Secs.…”