Modelling Dissipative Dynamics of r-mode Instability in Hybrid Stars
Abstract
Compact star cores reach extreme densities and may contain exotic dense-matter phases. Information about the exotic interiors of rapidly rotating pulsars can be inferred from r-mode oscillations, whose stability is governed by viscous dissipation. In this work, we model a compact star containing a possible mixed phase of hadronic and quark matter and employ a hybrid statistical framework based on Bayesian inference to infer the dissipation time scales associated with the hybrid phase. Using low-mass X-ray binaries (LMXB) timing observations together with mass-radius constraints from the Neutron Star Interior Composition Explorer (NICER) mission, we estimate the shear and bulk viscosity contributions to r-mode damping for a hybrid star of two layers. Our inference yields shear and bulk viscous dissipation time scales of τs=(4.99+0.49−0.52) × 108 T5/3s and τB=(2.150+1.23−0.60) × 1019 (T4 10−12+T2 10−6)−1Ω−2s respectively. The timescales thus obtained can be implemented to obtain the minima of the star's rotation frequency at Ω=451.87 Hz at temperature T=0.259 MeV for a hybrid star of mass $1.5$ M⊙ and Ω=517.47 Hz at T=0.234 MeV for M=1.75 M⊙. We find that the instability window obtained through the inference framework effectively explains the observed stability of millisecond pulsars in both the radio and LMXB populations, particularly for XTE J0929-314 and XTE J1807-294, J0437-4715, J2124-3358, respectively. These results demonstrate that Bayesian inference combined with r-mode phenomenology provides a powerful and observationally consistent framework for constraining the transport properties of dense hybrid matter.
Versions
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BibTeX
@misc{zala2026modelling,
title = {{Modelling Dissipative Dynamics of r-mode Instability in Hybrid Stars}},
author = {Khushbu Zala and Sreemoyee Sarkar},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.27465},
eprint = {2606.27465},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.27465},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Modelling Dissipative Dynamics of r-mode Instability in Hybrid Stars
AU - Khushbu Zala
AU - Sreemoyee Sarkar
PY - 2026
DA - 2026/09/16
PB - arXiv
DO - 10.48550/arxiv.2606.27465
UR - https://arxiv.org/abs/2606.27465
AB - Compact star cores reach extreme densities and may contain exotic dense-matter phases. Information about the exotic interiors of rapidly rotating pulsars can be inferred from r-mode oscillations, whose stability is governed by viscous dissipation. In this work, we model a compact star containing a possible mixed phase of hadronic and quark matter and employ a hybrid statistical framework based on Bayesian inference to infer the dissipation time scales associated with the hybrid phase. Using low-mass X-ray binaries (LMXB) timing observations together with mass-radius constraints from the Neutron Star Interior Composition Explorer (NICER) mission, we estimate the shear and bulk viscosity contributions to r-mode damping for a hybrid star of two layers. Our inference yields shear and bulk viscous dissipation time scales of τ_s=(4.99^+0.49_−0.52) × 10^8 T^5/3s and τ_B=(2.150^+1.23_−0.60) × 10^19 (T^4 10^−12+T^2 10^−6)^−1Ω^−2s respectively. The timescales thus obtained can be implemented to obtain the minima of the star's rotation frequency at Ω=451.87 Hz at temperature T=0.259 MeV for a hybrid star of mass $1.5$ M_⊙ and Ω=517.47 Hz at T=0.234 MeV for M=1.75 M_⊙. We find that the instability window obtained through the inference framework effectively explains the observed stability of millisecond pulsars in both the radio and LMXB populations, particularly for XTE J0929-314 and XTE J1807-294, J0437-4715, J2124-3358, respectively. These results demonstrate that Bayesian inference combined with r-mode phenomenology provides a powerful and observationally consistent framework for constraining the transport properties of dense hybrid matter.
ER -