We present a detailed analysis to clarify what determines the growth of the low-T/|W| instability in the context of rapidly rotating core collapse of massive stars. To this end, we perform three-dimensional core-collapse supernova (CCSN) simulations of a 27 M⊙ star including several updates in the general relativistic correction to gravity, the multi-energy treatment of heavy-lepton neutrinos, and the nuclear equation of state. Non-axisymmetric deformations are analyzed from the point of view of the time evolution of the pattern frequency and the corotation radius. The corotation radius is found to coincide with the convective layer in the proto neutron star (PNS). We propose a new mechanism to account for the growth of the low-T/|W| instability in the CCSN environment. Near the convective boundary where a small Brunt–Väisälä frequency is expected, Rossby waves propagating in the azimuthal direction at mid latitude induce non-axisymmetric unstable modes in both hemispheres. They merge with each other and finally become the spiral arm in the equatorial plane. We also investigate how the growth of the low-T/|W| instability impacts the neutrino and gravitational-wave signatures.

中文翻译：

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洞察具有中微子和引力波特征的三维旋转超新星模型中的非轴对称不稳定性

我们进行了详细的分析，以阐明是什么决定了低 T/|W| 的增长。在快速旋转的大质量恒星核心坍缩的背景下的不稳定性。为此，我们对一颗 27 M⊙ 恒星进行了 3D 核心坍缩超新星 (CCSN) 模拟，包括对引力的广义相对论校正、重轻子中微子的多能处理以及状态。从图案频率和共转半径的时间演化的角度分析了非轴对称变形。发现共转半径与原中子星 (PNS) 中的对流层一致。我们提出了一种新的机制来解释低 T/|W| 的增长。CCSN 环境不稳定。在对流边界附近，预计有一个小的 Brunt-Väisälä 频率，在中纬度沿方位角方向传播的罗斯贝波会在两个半球引起非轴对称不稳定模式。它们相互融合，最终成为赤道平面的旋臂。我们还研究了低 T/|W| 的增长情况。不稳定性影响中微子和引力波特征。