Particle Acceleration at the Pileup Collision of the Twin Shock
Particle Acceleration at the Pileup Collision of the Twin Shock
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DOI：
10.3847/1538-4357/ab4655
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
Xin Wang;J. Giacalone;Yihua Yan;M. Ding;Chuan Li;Hong Lu;H. Shan
中科院分区：
文献类型：
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作者：
Xin Wang;J. Giacalone;Yihua Yan;M. Ding;Chuan Li;Hong Lu;H. Shan
地面增强（GLE）事件通常与大型渐进太阳事件（如快速日冕物质抛射（CME））有关，但并非所有快速CME都会导致GLE事件。是否存在一种协调的日冕物质抛射，能够产生比正常的快速孤立日冕物质抛射更强、能量更高的GLE？在这里，我们提出了一个由双CME协调驱动的双激波方案，其中后激波赶上前激波并发生堆积碰撞。在本研究中，我们选择了2012年5月17日发生的第24个太阳活动周的第一个GLE事件作为一个例子，以调查可能与双激波的情况。我们使用动态蒙特卡罗方法来研究与GLE事件相关的能谱。在双激波情形下，前一激波产生的种子高能粒子可以有效地注入后一激波中进行再加速。结果，我们得到了在孪生激波演化的相关事件中具有不同行为的太阳高能粒子（SEP）的详细能谱。因此，我们预测在2012年5月17日SEP事件中，孪生激波的堆积碰撞将主导一个凹的能量谱斜率。
Ground-level enhancement (GLE) events are often associated with large gradual solar events such as fast coronal mass ejections (CMEs), but not all fast CMEs lead to GLE events. Is there a type of coordinated CME that could produce GLEs with larger intensity and higher energies than those in the normal fast isolated CMEs? Here we propose a twin-shock scenario driven by the twin CME coordinately, in which the posterior shock catches up with the preceding shock and has a pileup collision. In the present study, we chose the first GLE event of the solar cycle 24 occurring on 2012 May 17 as an example to investigate the probable association with the twin-shock scenario. We use a dynamic Monte Carlo method to examine the energy spectrum with relevance to the GLE event. In the twin-shock scenario, the seed energetic particles produced by the normal preceding shock can be injected into the posterior shock for reacceleration efficiently. As a result, we obtain the detailed energy spectrum of the solar energetic particles (SEPs) with different behaviors at the related episodes of the twin-shock evolution. Therefore, we predict that the pileup collision of the twin shock would dominate a concave energy spectral slope in the 2012 May 17 SEP event.