Gapless superfluidity in neutron stars: Thermal properties

Abstract

The interior of mature neutron stars is expected to contain superfluid neutrons and superconducting protons. The influence of temperature and currents on superfluid properties is studied within the self-consistent time-dependent nuclear energy-density functional theory. We find that this theory predicts the existence of a regime in which nucleons are superfluid (the order parameter remains finite) even though the energy spectrum of quasiparticle excitations exhibits no gap. We show that the disappearance of the gap leads to a specific heat that is not exponentially suppressed at low temperatures as in the BCS regime but can be comparable to that in the normal phase. Introducing some dimensionless effective superfluid velocity, we show that the behavior of the specific heat is essentially universal and we derive general approximate analytical formulas for applications to neutron-star cooling simulations.

28 pages, 6 figures

References in corpus (28)

• The ATNF Pulsar Catalogue
• Rapid Cooling of the Neutron Star in Cassiopeia A Triggered by Neutron Superfluidity in Dense Matter
• Cooling neutron star in the Cassiopeia~A supernova remnant: Evidence for superfluidity in the core
• Neutron stars - cooling and transport
• Collective mode of homogeneous superfluid Fermi gases in the BEC-BCS crossover
• Renormalization of the Hartree-Fock-Bogoliubov Equations in the Case of a Zero Range Pairing Interaction
• Superfluidity in nuclear systems and neutron stars
• From Brueckner Approach to Skyrme-type Energy Density Functional
• Measuring the Cooling of the Neutron Star in Cassiopeia A with all Chandra X-ray Observatory Detectors
• Effective contact pairing forces from realistic calculations in infinite homogeneous nuclear matter
• Superfluidity and Superconductivity in Neutron Stars
• Unified equations of state for cold non-accreting neutron stars with Brussels-Montreal functionals. II. Pasta phases in semi-classical approximation
• Diffusive nuclear burning in cooling simulations and application to new temperature data of the Cassiopeia A neutron star
• Upper limits on the rapid cooling of the Central Compact Object in Cas A
• Role of the symmetry energy and the neutron-matter stiffness on the tidal deformability of a neutron star with unified equations of state
• Unified description of neutron superfluidity in the neutron-star crust with analogy to anisotropic multi-band BCS superconductors
• Time-Dependent Density Functional Theory for Fermionic Superfluids: from Cold Atomic Gases, to Nuclei and Neutron Stars Crust
• Turning the nuclear energy density functional method into a proper effective field theory: reflections
• X-ray bounds on cooling, composition, and magnetic field of the Cassiopeia A neutron star and young central compact objects
• The cooling of the Central Compact Object in Cas A from 2006 to 2020
• Velocity-dependent energy gaps and dynamics of superfluid neutron stars
• Neutron specific heat in the crust of neutron stars from the nuclear band theory
• ${}^1$S${}_0$ pairing gaps, chemical potential and entrainment matrix in superfluid neutron-star cores for the Brussels-Montreal functionals
• Entrainment effects in neutron-proton mixtures within the nuclear-energy density functional theory. I. Low-temperature limit
• The entrainment matrix of a superfluid nucleon mixture at finite temperatures
• Entrainment effects in neutron-proton mixtures within the nuclear-energy density functional theory. II. Finite temperatures and arbitrary currents
• Nonlinear approach to the entrainment matrix of superfluid nucleon mixture at zero temperature
• Heat capacity of low density neutron matter: from quantum to classical regimes

Cited by in corpus (6)

• Gapless neutron superfluidity can explain the late time cooling of transiently accreting neutron stars
• Superfluid fraction in the crystalline crust of a neutron star: role of BCS pairing
• Time-dependent nuclear energy-density functional theory toolkit for neutron star crust: Dynamics of a nucleus in a neutron superfluid
• Gapless neutron superfluidity in the crust of the accreting neutron stars KS 1731-260 and MXB 1659-29
• Superfluid fraction in the crystalline crust of a neutron star: role of quantum zero-point motion of ions
• Thermodynamic stability of superflows in General Relativity and Newtonian gravity