标题： 中子星在全广义相对论中的不稳定性使用$Γ=2.75$理想流体 显示英文标题

标题： Neutron Star instabilities in full General Relativity using a $Γ=2.75$ ideal fluid

摘要： 我们展示了关于使用更刚性的状态方程（即理想流体的 $\Gamma=2.75$ 方程）对快速旋转的中子星多圈压模型的动力学条状模不稳定性影响的结果，这些模型完全处于广义相对论框架下。 我们确定了当绝热指数 $\Gamma$ 从 2 变化到 2.75 以模拟现实状态方程的行为时，不稳定参数 $\beta$ 的临界值的变化。特别是，我们表明条状模不稳定的起始阈值因这种刚性变化而降低，并且精确量化了临界参数 $\beta_c$ 的值的变化。 我们还扩展了对较低 $\beta$ 值的分析，并表明即使在由简单的多圈压状态方程描述的物质情况下，低β剪切不稳定性也存在。 显示英文摘要

摘要： We present results about the effect of the use of a stiffer equation of state, namely the ideal-fluid $\Gamma=2.75$ ones, on the dynamical bar-mode instability in rapidly rotating polytropic models of neutron stars in full General Relativity. We determine the change on the critical value of the instability parameter $\beta$ for the emergence of the instability when the adiabatic index $\Gamma$ is changed from 2 to 2.75 in order to mimic the behavior of a realistic equation of state. In particular, we show that the threshold for the onset of the bar-mode instability is reduced by this change in the stiffness and give a precise quantification of the change in value of the critical parameter $\beta_c$. We also extend the analysis to lower values of $\beta$ and show that low-beta shear instabilities are present also in the case of matter described by a simple polytropic equation of state.