RE-ACCELERATION OF NON-THERMAL PARTICLES AT WEAK COSMOLOGICAL SHOCK WAVES
RE-ACCELERATION OF NON-THERMAL PARTICLES AT WEAK COSMOLOGICAL SHOCK WAVES
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DOI：
10.1088/0004-637x/734/1/18
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发表时间：
2011-06-10
影响因子：
4.9
通讯作者：
Ryu, Dongsu
中科院分区：
文献类型：
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作者：
Kang, Hyesung;Ryu, Dongsu
我们研究扩散冲击加速度（DSA）的预先存在的，以及新注入的人口的非热，宇宙射线（CR）粒子在弱宇宙学冲击。假设简单的模型热漏注入和Alfvenic漂移，我们推导出分析，时间依赖性的解决方案的两个人口的CR加速在测试粒子制度。然后，我们将它们与冲击波的动力学DSA模拟结果进行比较，这些冲击波预计将在大规模结构形成的过程中形成于集群内介质和集群外围。我们表明，测试粒子的解决方案提供了一个很好的近似的压力和光谱的CR加速在这些弱冲击。由于注入是非常低效的弱冲击，预先存在的CR人口占主导地位的注入人口。如果由于预先存在的CR质子的压力是上游流中的气体热压力的约5%，则下游CR压力通常可以在马赫数M小于或类似于3的冲击下吸收冲击冲压压力的几个至10%，然而CR电子的再加速可以导致冲击后面的大量同步加速器发射。根据详细的模型参数，估计在M = 1.5时，激波上同步辐射的增强约为几个或几个，而在M = 3时，同步辐射的增强约为10（2）-10（3）。讨论了我们的研究结果对观测到的明亮射电遗迹的影响。
We examine diffusive shock acceleration (DSA) of the pre-existing as well as freshly injected populations of non-thermal, cosmic-ray (CR) particles at weak cosmological shocks. Assuming simple models for thermal leakage injection and Alfvenic drift, we derive analytic, time-dependent solutions for the two populations of CRs accelerated in the test-particle regime. We then compare them with the results from kinetic DSA simulations for shock waves that are expected to form in intracluster media and cluster outskirts in the course of large-scale structure formation. We show that the test-particle solutions provide a good approximation for the pressure and spectrum of CRs accelerated at these weak shocks. Since the injection is extremely inefficient at weak shocks, the pre-existing CR population dominates over the injected population. If the pressure due to pre-existing CR protons is about 5% of the gas thermal pressure in the upstream flow, the downstream CR pressure can absorb typically a few to 10% of the shock ram pressure at shocks with a Mach number M less than or similar to 3, yet the re-acceleration of CR electrons can result in a substantial synchrotron emission behind the shock. The enhancement in synchrotron radiation across the shock is estimated to be about a few to several for M similar to 1.5 and 10(2)-10(3) for M similar to 3, depending on the detail model parameters. The implication of our findings for observed bright radio relics is discussed.