Universal relation involving fundamental modes in two-fluid dark matter admixed neutron stars

Fuente: arXiv
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Main Authors: Sotani, Hajime, Kumar, Ankit
Format: Preprint
Published: 2025
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author Sotani, Hajime
Kumar, Ankit
author_facet Sotani, Hajime
Kumar, Ankit
contents We systematically investigate the fundamental oscillation frequencies of dark matter admixed neutron stars, focusing on models with self-interacting fermionic dark matter that couples to normal matter solely through gravity. The analysis is carried out within a two-fluid formalism under the relativistic Cowling approximation, where the perturbation equations follow from the linearized energy-momentum conservation laws of both components. We find that the mass-scaled fundamental frequencies of the nuclear (dark) fluid in dark core (halo) configurations exhibit a remarkably tight correlation with the total stellar compactness. This universality persists across the dark matter parameter space explored in this study and is largely insensitive to the choice of nuclear equation of state. In contrast, we also find the breakdown of such universality with the tidal deformability, i.e, the same frequencies show substantial deviations from universality when expressed in terms of the tidal deformability. These contrasting behaviors highlight possible observational imprints of dark matter in neutron star interiors.
format Preprint
id arxiv_https___arxiv_org_abs_2512_07105
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Universal relation involving fundamental modes in two-fluid dark matter admixed neutron stars
Sotani, Hajime
Kumar, Ankit
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
We systematically investigate the fundamental oscillation frequencies of dark matter admixed neutron stars, focusing on models with self-interacting fermionic dark matter that couples to normal matter solely through gravity. The analysis is carried out within a two-fluid formalism under the relativistic Cowling approximation, where the perturbation equations follow from the linearized energy-momentum conservation laws of both components. We find that the mass-scaled fundamental frequencies of the nuclear (dark) fluid in dark core (halo) configurations exhibit a remarkably tight correlation with the total stellar compactness. This universality persists across the dark matter parameter space explored in this study and is largely insensitive to the choice of nuclear equation of state. In contrast, we also find the breakdown of such universality with the tidal deformability, i.e, the same frequencies show substantial deviations from universality when expressed in terms of the tidal deformability. These contrasting behaviors highlight possible observational imprints of dark matter in neutron star interiors.
title Universal relation involving fundamental modes in two-fluid dark matter admixed neutron stars
topic High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2512.07105