标题： 关于高能变源1ES 1011+496的光谱曲率：空间粒子扩散的影响 显示英文标题

标题： On the spectral curvature of VHE blazar 1ES\,1011+496: Effect of spatial particle diffusion

摘要： 对甚高能（VHE）源 1ES 1011+496 的宽波段光谱行为的详细多时段研究为我们提供了有关粒子分布的重要信息。 来自 Swift-UVOT/Swift-XRT/Fermi-LAT 在三个不同时间段内的光学/紫外/X射线/$\gamma$射线的同时观测数据，结合来自 HAGAR VHE 望远镜阵列的信息。 在 Fermi-LAT 能量范围内的长期流量变化明显呈对数正态分布。 可以看到，1ES 1011+496 的宽带谱能量分布（SED）可以通过同步辐射和同步自康普顿辐射模型成功重现。 值得注意的是，在 X 射线能量下的光子谱曲率表明，底层粒子分布需要从简单的幂律平滑过渡到带有指数截断的幂律或平滑断裂幂律分布，这可能是在粒子从主辐射区逃逸时表现出能量依赖性的情况下产生的。 具体而言，如果粒子逃逸率与能量的关系为$E^{0.5}$，则观测到的光子谱与各个时间段观察到的一致。 显示英文摘要

摘要： A detailed multi-epoch study of the broadband spectral behaviour of the very high energy (VHE) source, 1ES\,1011+496, provides us with valuable information regarding the underlying particle distribution. Simultaneous observations of the source at optical/ UV/ X-ray/ $\gamma$-ray during three different epochs, as obtained from Swift-UVOT/ Swift-XRT/ Fermi-LAT, are supplemented with the information available from the VHE telescope array, HAGAR. The longterm flux variability at the Fermi-LAT energies is clearly found to be lognormal. It is seen that the broadband spectral energy distribution (SED) of 1ES\,1011+496 can be successfully reproduced by synchrotron and synchrotron self Compton emission models. Notably, the observed curvature in the photon spectrum at X-ray energies demands a smooth transition of the underlying particle distribution from a simple power law to a power law with an exponential cutoff or a smooth broken power law distribution, which may possibly arise when the escape of the particles from the main emission region is energy dependent. Specifically, if the particle escape rate is related to its energy as $E^{0.5}$ then the observed photon spectrum is consistent with the ones observed during the various epochs.