Shear oscillations in neutron stars and the nuclear symmetry energy

Fuente: arXiv
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Autor principal: Sotani, Hajime
Formato: Preprint
Publicado: 2024
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author Sotani, Hajime
author_facet Sotani, Hajime
contents The shear and interface modes excited inside the neutron star due to the presence of elasticity depend on the properties of both the crust and core region. To examine how such eigenfrequencies depend on the neutron star properties, we solve the eigenvalue problem by adopting the relativistic Cowling approximation. Then, we confirm that the number of the interface modes excited in the star is generally equivalent to the number of the interface where the shear modulus discontinuously becomes zero, but we also find that the number of interface modes becomes smaller than that of the interface for the stellar model with lower or higher value of the slope parameter $L$. Furthermore, we derive the empirical relations for expressing the shear modes and one of the interface modes ($i_1$-mode in the text), which is the mode whose amplitude becomes dominant at the interface between the crust and envelopes and at the interface between the phases of slablike and cylindrical nuclei. At the end, we also show the possibility of identifying the higher QPO frequencies observed in GRB 200415A with the shear oscillations, as an alternative possibility instead of the torsional oscillations.
format Preprint
id arxiv_https___arxiv_org_abs_2401_08382
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Shear oscillations in neutron stars and the nuclear symmetry energy
Sotani, Hajime
High Energy Astrophysical Phenomena
Nuclear Theory
The shear and interface modes excited inside the neutron star due to the presence of elasticity depend on the properties of both the crust and core region. To examine how such eigenfrequencies depend on the neutron star properties, we solve the eigenvalue problem by adopting the relativistic Cowling approximation. Then, we confirm that the number of the interface modes excited in the star is generally equivalent to the number of the interface where the shear modulus discontinuously becomes zero, but we also find that the number of interface modes becomes smaller than that of the interface for the stellar model with lower or higher value of the slope parameter $L$. Furthermore, we derive the empirical relations for expressing the shear modes and one of the interface modes ($i_1$-mode in the text), which is the mode whose amplitude becomes dominant at the interface between the crust and envelopes and at the interface between the phases of slablike and cylindrical nuclei. At the end, we also show the possibility of identifying the higher QPO frequencies observed in GRB 200415A with the shear oscillations, as an alternative possibility instead of the torsional oscillations.
title Shear oscillations in neutron stars and the nuclear symmetry energy
topic High Energy Astrophysical Phenomena
Nuclear Theory
url https://arxiv.org/abs/2401.08382