重联电场加速电子的能谱：指数律还是幂律？
Energy Spectrum of the Electrons Accelerated by a Reconnection Electric Field: Exponential or Power Law?
摘要：
重联区附近的直流电场被认为是太阳耀斑中加速质子和电子的有效机制。在重联电场加速电子的模拟中，一般认为电子能谱是幂律的。然而，在大多数文献中，电场和磁场是独立选择的。在本文中，我们进行测试粒子模拟的电子加速在重联磁场，其中的电场和磁场都采用从数值模拟的MHD方程。结果表明，被加速的电子在高能量下呈现出截断的幂律能谱，其尾部为指数形，这与扩散冲击波加速的情况类似。研究了重联参数对谱特征的影响，如磁场的纵向分量和横向分量以及电流片的大小。有人建议，直流电场单独可能无法重现所观察到的单或双幂律分布。
英文摘要：
The direct current (DC) electric field near the reconnection region has been proposed as an effective mechanism to accelerate protons and electrons in solar flares. A power-law energy spectrum was generally claimed in the simulations of electron acceleration by the reconnection electric field. However in most of the literature, the electric and magnetic fields were chosen independently. In this paper, we perform test-particle simulations of electron acceleration in a reconnecting magnetic field, where both the electric and magnetic fields are adopted from numerical simulations of the MHD equations. It is found that the accelerated electrons present a truncated power-law energy spectrum with an exponential tail at high energies, which is analogous to the case of diffusive shock acceleration. The influences of reconnection parameters on the spectral feature are also investigated, such as the longitudinal and transverse components of the magnetic field and the size of the current sheet. It is suggested that the DC electric field alone might not be able to reproduce the observed single or double power-law distributions.
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。
