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arXiv 2207.06804astro-ph.HE
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开普勒SNR中硬X射线发射的空间分辨研究:粒子加速不同区域的指示

A spatially resolved study of hard X-ray emission in Kepler's SNR: indications of different regimes of particle acceleration

Vincenzo Sapienza, Marco Miceli, Aya Bamba, Satoru Katsuda, Tsutomu Nagayoshi, Yukikatsu Terada, Fabrizio Bocchino, Salvatore Orlando, Giovanni Peres

摘要:

年轻超新星遗迹的同步加速器X射线辐射是研究激波前沿加速的高能电子布居和加速过程的有力诊断工具。我们进行了空间分辨光谱分析NuSTAR和XMM-牛顿观测的年轻开普勒的SNR,旨在详细研究其非热发射的硬X射线。我们选择了一组区域周围的边缘的壳和提取相应的光谱。采用有限损耗区的同步辐射模型对光谱进行了分析,以约束同步辐射截止能量对激波速度的依赖性。我们确定了两种不同的制度的粒子加速,其特征在于不同的玻姆因子。在北部,那里的冲击与致密的星周介质(CSM)相互作用,我们发现一个更有效的加速比在南部,那里的冲击速度更高,并没有迹象表明冲击与致密的CSM相互作用。我们的研究结果表明,在激波-CSM相互作用产生放大和湍流磁场的区域,加速过程的效率提高。通过结合硬X射线光谱与射电和开普勒信噪比的$γ-$射线观测,我们模拟了光谱能量分布。根据我们的结果,我们建议,所观察到的$γ-$射线发射主要是强子,并起源于北部的壳。

英文摘要:

Synchrotron X-ray emission in young supernova remnants (SNRs) is a powerful diagnostic tool to study the population of high energy electrons accelerated at the shock front and the acceleration process. We performed a spatially resolved spectral analysis of NuSTAR and XMM-Newton observations of the young Kepler's SNR, aiming to study in detail its non-thermal emission in hard X-rays. We selected a set of regions all around the rim of the shell and extracted the corresponding spectra. The spectra were analyzed by adopting a model of synchrotron radiation in the loss-limited regime, to constrain the dependence of the cutoff energy of the synchrotron radiation on the shock velocity. We identify two different regimes of particle acceleration, characterized by different Bohm factors. In the north, where the shock interacts with a dense circumstellar medium (CSM), we found a more efficient acceleration than in the south, where the shock velocity is higher and there are no signs of shock interaction with dense CSM. Our results suggest an enhanced efficiency of the acceleration process in regions where the shock-CSM interaction generates an amplified and turbulent magnetic field. By combining hard X-ray spectra with radio and $γ-$ray observations of Kepler's SNR, we modelled the spectral energy distribution. In the light of our results we propose that the observed $γ-$ray emission is mainly hadronic, and originates in the northern part of the shell.

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