Signatures of $K^-$ condensation on neutron star structure and $f-$mode frequencies

Fuente: arXiv
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Autores principales: Roy, Debanjan Guha, Banik, Sarmistha
Formato: Preprint
Publicado: 2025
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author Roy, Debanjan Guha
Banik, Sarmistha
author_facet Roy, Debanjan Guha
Banik, Sarmistha
contents Antikaon ($K^-$) condensation within neutron star matter (NS) depends on the antikaon-nucleon interaction potential ($U_K$). Appearance of $K^-$ generally softens the equation of state (EOS). The impact of this softening on the structure of the NS can be leveraged to find a telltale sign of the phase transition from nucleonic matter to $K^-$ condensation. To investigate the impact of $K^-$ condensation on NS properties using a Bayesian inference framework, we choose two sets of RMF model parameters to obtain a stiff (DD2) and relatively soft (FSU) nucleonic EOS, and explore a wide range of optical potential depths. Multimessenger observations from NICER and LIGO/Virgo constrain the optical potential values to $U_K = -104.72^{+13.82}_{-12.48}$ MeV and $U_K = -66.46^{+2.47}_{-3.42}$ MeV for the stiff and soft cases, respectively. Deeper $K^-$ potentials trigger condensation at a lower density, softening the EOS and lowering the corresponding maximum masses. While slopes of mass-radius and tidal deformability curves overlap between nucleonic and exotic EOSs, their curvature and $f-$mode oscillation properties (frequency and damping time) reveal features attributable to EOS softening. However, distinguishing the specific exotic degrees of freedom responsible for the softening remains an open challenge.
format Preprint
id arxiv_https___arxiv_org_abs_2509_15376
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Signatures of $K^-$ condensation on neutron star structure and $f-$mode frequencies
Roy, Debanjan Guha
Banik, Sarmistha
Nuclear Theory
High Energy Astrophysical Phenomena
Antikaon ($K^-$) condensation within neutron star matter (NS) depends on the antikaon-nucleon interaction potential ($U_K$). Appearance of $K^-$ generally softens the equation of state (EOS). The impact of this softening on the structure of the NS can be leveraged to find a telltale sign of the phase transition from nucleonic matter to $K^-$ condensation. To investigate the impact of $K^-$ condensation on NS properties using a Bayesian inference framework, we choose two sets of RMF model parameters to obtain a stiff (DD2) and relatively soft (FSU) nucleonic EOS, and explore a wide range of optical potential depths. Multimessenger observations from NICER and LIGO/Virgo constrain the optical potential values to $U_K = -104.72^{+13.82}_{-12.48}$ MeV and $U_K = -66.46^{+2.47}_{-3.42}$ MeV for the stiff and soft cases, respectively. Deeper $K^-$ potentials trigger condensation at a lower density, softening the EOS and lowering the corresponding maximum masses. While slopes of mass-radius and tidal deformability curves overlap between nucleonic and exotic EOSs, their curvature and $f-$mode oscillation properties (frequency and damping time) reveal features attributable to EOS softening. However, distinguishing the specific exotic degrees of freedom responsible for the softening remains an open challenge.
title Signatures of $K^-$ condensation on neutron star structure and $f-$mode frequencies
topic Nuclear Theory
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2509.15376