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arXiv · 2502.03973

Axisymmetric stability of neutron stars as extreme rotators in massive scalar-tensor theory

Alan Tsz-Lok Lam·Kalin V. Staykov·Hao-Jui Kuan·Daniela D. Doneva·Stoytcho S. Yazadjiev
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Abstract

Differentially rotating scalarized neutron stars, mimickers of binary merger remnants, can possess an enormous angular momentum larger than what could possibly be sustained in a neutron star in general relativity by about one order of magnitude. A natural question to ask is whether these solutions are stable and thus can realize in a binary coalescence. With this motivation in mind, we examine the criterion of dynamical stability against axisymmetric perturbations for these ultra-rotators by numerically tracking their nonlinear evolution in an axisymmetric setup. We demonstrate that the turning-point criterion still serves as a sufficient condition for asymmetric (in)stability. Our findings open an interesting question of whether the merger of two scalarized neutron stars can produce (possibly short-lived) ultra-highly rotating merger remnants.

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Alan Tsz-Lok Lam, Kalin V. Staykov, Hao-Jui Kuan, Daniela D. Doneva, Stoytcho S. Yazadjiev. 2025-02-06. Axisymmetric stability of neutron stars as extreme rotators in massive scalar-tensor theory. https://arxiv.org/abs/2502.03973

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