Gapless neutron superfluidity can explain the late time cooling of transiently accreting neutron stars

Fuente: arXiv
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Main Authors: Allard, Valentin, Chamel, Nicolas
Format: Preprint
Published: 2024
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author Allard, Valentin
Chamel, Nicolas
author_facet Allard, Valentin
Chamel, Nicolas
contents The current interpretation of the observed late time cooling of transiently accreting neutron stars in low-mass X-ray binaries during quiescence requires the suppression of neutron superfluidity in their crust at variance with recent ab initio many-body calculations of dense matter. Focusing on the two emblematic sources KS~1731$-$260 and MXB~1659$-$29, we show that their thermal evolution can be naturally explained by considering the existence of a neutron superflow driven by the pinning of quantized vortices. Under such circumstances, we find that the neutron superfluid can be in a gapless state in which the specific heat is dramatically increased compared to that in the classical BCS state assumed so far, thus delaying the thermal relaxation of the crust. We have performed neutron-star cooling simulations taking into account gapless superfluidity and we have obtained excellent fits to the data thus reconciling astrophysical observations with microscopic theories. The imprint of gapless superfluidity on other observable phenomena is briefly discussed.
format Preprint
id arxiv_https___arxiv_org_abs_2403_07740
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Gapless neutron superfluidity can explain the late time cooling of transiently accreting neutron stars
Allard, Valentin
Chamel, Nicolas
High Energy Astrophysical Phenomena
Superconductivity
Nuclear Theory
The current interpretation of the observed late time cooling of transiently accreting neutron stars in low-mass X-ray binaries during quiescence requires the suppression of neutron superfluidity in their crust at variance with recent ab initio many-body calculations of dense matter. Focusing on the two emblematic sources KS~1731$-$260 and MXB~1659$-$29, we show that their thermal evolution can be naturally explained by considering the existence of a neutron superflow driven by the pinning of quantized vortices. Under such circumstances, we find that the neutron superfluid can be in a gapless state in which the specific heat is dramatically increased compared to that in the classical BCS state assumed so far, thus delaying the thermal relaxation of the crust. We have performed neutron-star cooling simulations taking into account gapless superfluidity and we have obtained excellent fits to the data thus reconciling astrophysical observations with microscopic theories. The imprint of gapless superfluidity on other observable phenomena is briefly discussed.
title Gapless neutron superfluidity can explain the late time cooling of transiently accreting neutron stars
topic High Energy Astrophysical Phenomena
Superconductivity
Nuclear Theory
url https://arxiv.org/abs/2403.07740