Nonthermal Emissions from Particles Accelerated by Turbulence in Clusters of Galaxies
Nonthermal Emissions from Particles Accelerated by Turbulence in Clusters of Galaxies
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DOI：
10.1086/345599
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发表时间：
2002-10
期刊：
影响因子：
--
通讯作者：
Y. Fujita;M. Takizawa;C. Sarazin
中科院分区：
文献类型：
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作者：
Y. Fujita;M. Takizawa;C. Sarazin
我们考虑星系团的非热辐射产生的粒子加速通过共振散射的阿尔文波驱动的流体湍流通过莱特希尔机制在团内介质。我们假设湍流是由集群合并驱动的。我们发现共振阿尔文波可以通过共振散射将电子加速到γ ~ 105。我们还发现，如果团簇中存在γ ~ 103的电子池，则湍流共振加速可以给电子足够的能量，产生观测到的弥散射电遗迹辐射。如果团簇中的磁场足够小（10 μG）或流体湍流谱比Kolmogorov定律更平坦，这种机制也可以解释观察到的团簇硬X射线发射。在观测到漫射无线电发射的区域，可以用Astro-E2观测到流体湍流。虽然星系团形成前的非引力加热（预热）使射电光度和X射线温度之间的关系变陡，但我们预测的关系仍然比观测到的关系平坦。
We consider nonthermal emission from clusters of galaxies produced by particle acceleration by resonant scattering of Alfvén waves driven by fluid turbulence through the Lighthill mechanism in the intracluster medium. We assume that the turbulence is driven by cluster mergers. We find that the resonant Alfvén waves can accelerate electrons up to γ ~ 105 through resonant scattering. We also find that the turbulent resonant acceleration can give enough energy to electrons to produce the observed diffuse radio relic emission from clusters if the clusters have a pool of electrons with γ ~ 103. This mechanism can also explain the observed hard X-ray emission from clusters if the magnetic field in a cluster is small enough (≲μG) or the fluid turbulence spectrum is flatter than the Kolmogorov law. The fluid turbulence could be observed with Astro-E2 in the regions where diffuse radio emission is observed. Although nongravitational heating before cluster formation (preheating) steepens a relation between radio luminosity and X-ray temperature, our predicted relation is still flatter than the observed one.