Superfluid density in linear response theory : pulsar glitches from the inner crust of neutron stars

Fuente: arXiv
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Autores principales: Almirante, Giorgio, Urban, Michael
Formato: Preprint
Publicado: 2025
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author Almirante, Giorgio
Urban, Michael
author_facet Almirante, Giorgio
Urban, Michael
contents The question of whether there are enough superfluid neutrons in the inner crust of neutron stars to explain pulsar glitches remains a topic of debate. Previous band structure calculations suggest that the entrainment effect significantly reduces the superfluid density. In this letter, a new derivation of the BCS expression for the superfluid density is given. We compute it in the superfluid band theory framework through linear response theory, for a small relative velocity between superfluid and normal components, under the assumption that the pairing gap in the rest frame of the superfluid is constant and not affected by the perturbation. Our result suggests that a formula extensively used in neutron star physics is incomplete. Numerical evaluations for two realistic configurations reveal that the previously neglected contribution drastically alters the picture of the superfluid reservoir in the inner crust of neutron stars, suggesting that about 90% of the neutrons are effectively superfluid.
format Preprint
id arxiv_https___arxiv_org_abs_2503_21635
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Superfluid density in linear response theory : pulsar glitches from the inner crust of neutron stars
Almirante, Giorgio
Urban, Michael
Nuclear Theory
Quantum Gases
The question of whether there are enough superfluid neutrons in the inner crust of neutron stars to explain pulsar glitches remains a topic of debate. Previous band structure calculations suggest that the entrainment effect significantly reduces the superfluid density. In this letter, a new derivation of the BCS expression for the superfluid density is given. We compute it in the superfluid band theory framework through linear response theory, for a small relative velocity between superfluid and normal components, under the assumption that the pairing gap in the rest frame of the superfluid is constant and not affected by the perturbation. Our result suggests that a formula extensively used in neutron star physics is incomplete. Numerical evaluations for two realistic configurations reveal that the previously neglected contribution drastically alters the picture of the superfluid reservoir in the inner crust of neutron stars, suggesting that about 90% of the neutrons are effectively superfluid.
title Superfluid density in linear response theory : pulsar glitches from the inner crust of neutron stars
topic Nuclear Theory
Quantum Gases
url https://arxiv.org/abs/2503.21635