Radio afterglow of magnetars’ giant flares
Radio afterglow of magnetars’ giant flares
复制标题
DOI：
10.1093/mnras/stab2151
复制
发表时间：
2021-06
期刊：
影响因子：
--
通讯作者：
Riddhi Mehta;M. Barkov;M. Lyutikov
中科院分区：
文献类型：
--
作者：
Riddhi Mehta;M. Barkov;M. Lyutikov
我们建立了SGR 1806-20巨大耀斑的射电余辉模型，这是由于磁主导云（类似于太阳日冕物质抛射（cme））与星际介质（ISM）的相互作用而产生的。日冕物质抛射被建模为球形结构。CME首先与磁星的风平流，然后与ISM相互作用，产生强烈的向前冲击和复杂的向后排气流。利用三维磁流体力学模拟，我们研究了CME磁场相对于ISM磁场的各种相对构型。研究表明，前向激波的动力学主要遵循Sedov-Taylor冲击波，而激波介质的内部结构被回流极大地改变，形成了多重激波结构。我们使用两个假设计算合成同步加速器发射率图和光曲线：(i)磁场压缩；（ii）冲击时磁场的放大。我们发现磁场放大的模型能更好地解释观测到的射电发射。
We develop a model for the radio afterglow of the giant flare of SGR 1806-20 arising due to the interaction of magneticallydominated cloud, an analogue of Solar Coronal Mass Ejections (CMEs), with the interstellar medium (ISM). The CME is modeled as a spheromak-like configuration. The CME is first advected with the magnetar’s wind and later interacts with the ISM, creating a strong forward shock and complicated backwards exhaust flow. Using three-dimensional magnetohydrodynamic simulations, we study various relative configurations of the magnetic field of the CME with respect to the ISM’s magnetic field. We show that the dynamics of the forward shock mostly follows the Sedov-Taylor blastwave, while the internal structure of the shocked medium is considerably modified by the back flow, creating a multiple shock configuration. We calculate synthetic synchrotron emissivity maps and light curves using two assumptions: (i) magnetic field compression; (ii) amplification of the magnetic field at the shock. We find that models with magnetic field amplification account better for the observed radio emission.