arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1405.2144astro-ph.HEgr-qc
收藏

磁对差速旋转中子星低T/ |W|不稳定性的影响

Magnetic effects on the low-T/|W| instability in differentially rotating neutron stars

Curran D. Muhlberger, Fatemeh Hossein Nouri, Matthew D. Duez, Francois Foucart, Lawrence E. Kidder, Christian D. Ott, Mark A. Scheel, Béla Szilágyi, Saul A. Teukolsky

摘要:

质子中子星的动力学不稳定性可能会产生引力波,对它的观测可以揭示核心坍缩超新星的物理学。当这些恒星具有足够的差动自转时,它们容易受到剪切不稳定性(“低T/ |W|不稳定性”)的影响,但这种自转也可以将磁场放大到对恒星物质动力学有相当大影响的强度。利用一个新的磁流体力学谱爱因斯坦程序模块,我们模拟了一个差分旋转中子星的全三维研究磁场对这种不稳定性的影响。虽然强的环形场被预测为抑制低T/ |W|不稳定性,我们发现,他们这样做,只有在一个小范围的场强。在4 e13 G以下,极向种子场不会足够快地在不稳定性饱和之前产生影响,而在5e 14 G以上,磁不稳定性实际上可以放大全局四极模(这个阈值实际上可能更低,因为小尺度的磁不稳定性仍然难以数值解决)。因此,从这样的系统观测引力波的前景实际上在大部分磁参数空间上并没有减少。此外,我们报告的详细发展的低T/ |W|不稳定性,包括其增长率,强烈依赖于特定的数值方法。我们采用的高阶方法表明,增长可能比以前的一些模拟中发现的要慢得多。

英文摘要:

Dynamical instabilities in protoneutron stars may produce gravitational waves whose observation could shed light on the physics of core-collapse supernovae. When born with sufficient differential rotation, these stars are susceptible to a shear instability (the "low-T/|W| instability"), but such rotation can also amplify magnetic fields to strengths where they have a considerable impact on the dynamics of the stellar matter. Using a new magnetohydrodynamics module for the Spectral Einstein Code, we have simulated a differentially-rotating neutron star in full 3D to study the effects of magnetic fields on this instability. Though strong toroidal fields were predicted to suppress the low-T/|W| instability, we find that they do so only in a small range of field strengths. Below 4e13 G, poloidal seed fields do not wind up fast enough to have an effect before the instability saturates, while above 5e14 G, magnetic instabilities can actually amplify a global quadrupole mode (this threshold may be even lower in reality, as small-scale magnetic instabilities remain difficult to resolve numerically). Thus, the prospects for observing gravitational waves from such systems are not in fact diminished over most of the magnetic parameter space. Additionally, we report that the detailed development of the low-T/|W| instability, including its growth rate, depends strongly on the particular numerical methods used. The high-order methods we employ suggest that growth might be considerably slower than found in some previous simulations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑