Axion-angle dependence of the rotational and tidal properties of PNJL quark stars
Abstract
We investigate how a fixed, spatially uniform axion angle modifies the rotational and static tidal properties of self-bound quark stars in general relativity, using an axion-extended Polyakov-loop Nambu--Jona-Lasinio equation of state. We vary θ from $0$ to π while holding the remaining model parameters fixed, and compute the leading-order moment of inertia and the second-order spin-induced quadrupole moment and mass shift. The calculation includes finite-surface-density contributions to the rotational mass shift and static tidal response. Across this range, the static maximum mass increases from $1.68$ to 1.95 M⊙, remaining below the lower edge of the quoted 1σ timing interval for PSR~J0740+6620. At M=1.338 M⊙, the moment of inertia increases by 13% and the dimensionless tidal deformability rises from $342$ to $547$. Over the common mass range examined, the differences in the moment of inertia between adjacent sampled angles exceed the tested interpolation and table-resolution sensitivities. Despite these changes, joint fits to the five sequences describe the I̅--C and I-Love-Q relations with maximum departures of 2.7% and 0.4%, respectively, over the fitted domains. The predicted binary tidal-deformability curves lie within the estimated 90\% credible region of the adopted GW170817 posterior over the mass-ratio ranges examined. Within this EOS family, stellar properties vary appreciably with θ, while the normalized quantities admit accurate joint fits across the five sequences.
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BibTeX
@misc{islam2026axionangle,
title = {{Axion-angle dependence of the rotational and tidal properties of PNJL quark stars}},
author = {Safiqul Islam and Ayan Banerjee and Javlon Rayimbaev and Safyan Mukhtar},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.38343},
eprint = {2610.38343},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.38343},
}
RIS
TY - UNPB
TI - Axion-angle dependence of the rotational and tidal properties of PNJL quark stars
AU - Safiqul Islam
AU - Ayan Banerjee
AU - Javlon Rayimbaev
AU - Safyan Mukhtar
PY - 2026
DA - 2026/10/28
PB - arXiv
DO - 10.48550/arxiv.2610.38343
UR - https://arxiv.org/abs/2610.38343
AB - We investigate how a fixed, spatially uniform axion angle modifies the rotational and static tidal properties of self-bound quark stars in general relativity, using an axion-extended Polyakov-loop Nambu--Jona-Lasinio equation of state. We vary θ from $0$ to π while holding the remaining model parameters fixed, and compute the leading-order moment of inertia and the second-order spin-induced quadrupole moment and mass shift. The calculation includes finite-surface-density contributions to the rotational mass shift and static tidal response. Across this range, the static maximum mass increases from $1.68$ to 1.95 M_⊙, remaining below the lower edge of the quoted 1σ timing interval for PSR~J0740+6620. At M=1.338 M_⊙, the moment of inertia increases by 13% and the dimensionless tidal deformability rises from $342$ to $547$. Over the common mass range examined, the differences in the moment of inertia between adjacent sampled angles exceed the tested interpolation and table-resolution sensitivities. Despite these changes, joint fits to the five sequences describe the I̅--C and I-Love-Q relations with maximum departures of 2.7% and 0.4%, respectively, over the fitted domains. The predicted binary tidal-deformability curves lie within the estimated 90\% credible region of the adopted GW170817 posterior over the mass-ratio ranges examined. Within this EOS family, stellar properties vary appreciably with θ, while the normalized quantities admit accurate joint fits across the five sequences.
ER -