Constraining the efficiency of cosmic ray acceleration by cluster shocks
Constraining the efficiency of cosmic ray acceleration by cluster shocks
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DOI：
10.1093/mnras/stw584
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发表时间：
2016-03
影响因子：
4.8
通讯作者：
F. Vazza;M. Brüggen;D. Wittor;C. Gheller;D. Eckert;M. Stubbe
中科院分区：
文献类型：
--
作者：
F. Vazza;M. Brüggen;D. Wittor;C. Gheller;D. Eckert;M. Stubbe
我们用Enzo网格模拟研究了无碰撞结构形成激波对宇宙线的加速作用。来自费米卫星的数据使星系团能够用作粒子加速模型的试验台。基于先进的宇宙学模拟，包括气体和宇宙射线物理的不同处方，我们使用预测的{\伽马}射线发射来约束激波加速效率。我们推断，宇宙冲击的效率平均必须为0.1%，特别是对2<；M<；5合并冲击，这是星系团内介质热化的主要原因。这些结果都来自非辐射和辐射运行，包括来自活动星系核的反馈，以及对类似MACSJ1752.0+0440的星系团的变焦重新模拟。我们报告的加速效率的极限比文献中所假设的要低。结合星系团中射电发射的信息，似乎不可避免地要修订目前对ICM中激波加速的理解。
We study the acceleration of cosmic rays by collisionless structure formation shocks with ENZO grid simulations. Data from the FERMI satellite enable the use of galaxy clusters as a testbed for particle acceleration models. Based on advanced cosmological simulations that include different prescriptions for gas and cosmic rays physics, we use the predicted {\gamma}-ray emission to constrain the shock acceleration efficiency. We infer that the efficiency must be on average <0.1% for cosmic shocks, particularly for the 2<M<5 merger shocks that are mostly responsible for the thermalisation of the intracluster medium. These results emerge, both, from non-radiative and radiative runs including feedback from active galactic nuclei, as well as from zoomed resimulations of a cluster resembling MACSJ1752.0+0440. The limit on the acceleration efficiency we report is lower than what has been assumed in the literature so far. Combined with the information from radio emission in clusters, it appears that a revision of the present understanding of shock acceleration in the ICM is unavoidable.