Pair Plasma in Super-QED Magnetic Fields and the Hard X-Ray/Optical Emission of Magnetars
Pair Plasma in Super-QED Magnetic Fields and the Hard X-Ray/Optical Emission of Magnetars
复制标题
超级 QED 磁场中的配对等离子体和磁星的硬 X 射线/光学发射
DOI：
10.3847/1538-4357/abbe87
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
A. Kostenko
中科院分区：
文献类型：
--
作者：
C. Thompson;A. Kostenko
计算了在超强磁场存在下的跨相对论对等离子体发射的光子谱，发现它与静止磁星的硬X射线谱有着显著的相似之处。这种发射是由对湮灭，与弱磁化对等离子体相比，显示出类似于韧致辐射的扩展低频尾部。电子-正电子湮灭/散射、双光子对产生和光子-e ±散射的截面采用了我们早期的从头计算量子电动力学计算中的区域B B Q。仔细注意的u-通道散射共振。磁层弧锚定在强烈的地壳剪切区，并达到约两倍的磁星半径被确定为持久的硬X射线发射的网站。我们推导出一个新的和稳定的磁层电路的配置，与高等离子体密度维持欧姆加热和原位对创建。对来源于非本地的光子碰撞在弱电流区，如极冠。湮灭韧致辐射延伸到光学红外波段，等离子体截止的位置。磁星上层大气经历了强电流驱动的离子声湍流的增长，这可能会限制正电子的扩散。相干光红外辐射的约束附近所观察到的通量诱导散射。这个模型适应快速的X射线增亮的激活磁星，集中的热热点，和次显性的热X射线发射的一些活动磁星。电流注入归因于连续的磁编织，如Thompson、Yang和Ortiz的全局屈服计算所示。
The photon spectrum emitted by a transrelativistic pair plasma is calculated in the presence of an ultrastrong magnetic field, and is shown to bear a remarkable resemblance to the rising hard X-ray spectra of quiescent magnetars. This emission is powered by pair annihilation which, in contrast with a weakly magnetized pair plasma, shows an extended low-frequency tail similar to bremsstrahlung. Cross sections for electron–positron annihilation/scattering, two-photon pair creation, and photon-e ± scattering are adopted from our earlier ab initio quantum electrodynamic calculations in the regime ≫ B ≫ B Q. Careful attention is given to the u-channel scattering resonance. Magnetospheric arcades anchored in zones of intense crustal shear and reaching about twice the magnetar radius are identified as the sites of the persistent hard X-ray emission. We deduce a novel and stable configuration for the magnetospheric circuit, with a high plasma density sustained by ohmic heating and in situ pair creation. Pairs are sourced nonlocally by photon collisions in zones with weak currents, such as the polar cap. Annihilation bremsstrahlung extends to the optical–IR band, where the plasma cutoff is located. The upper magnetar atmosphere experiences strong current-driven growth of ion-acoustic turbulence, which may limit positron diffusion. Coherent optical–IR emission is bounded near the observed flux by induced scattering. This model accommodates the rapid X-ray brightening of an activating magnetar, concentrated thermal hotspots, and the subdominant thermal X-ray emission of some active magnetars. Current injection is ascribed to continuous magnetic braiding, as seen in the global yielding calculations of Thompson, Yang, and Ortiz.