论文标题
限制剪切加速度模型，以进行大规模的X射线发射
Constraining the shear acceleration model for the X-ray emission of large-scale extragalactic jets
论文作者
论文摘要
大型（$> 1 $ kpc）量表的强大X射线排放的性质仍在争论中。通过电子在GEV频段缺乏γ射线发射的挑战，挑战了电子CMB逆综合散射的情况。另一种替代性假设由不同的超高能电子群体进行同步发射。在这里，我们提出了应用这种情况的具体尝试，探索了特定模型，其中超高能电子被加速在射流周围的剪切层中加速。我们将研究限制为非相关流，而粒子加速度则由Fokker-Planck方程处理。观察到的低能（无线电，光学）和X射线发射之间的关系促使我们假设所需的预加速颗粒所需的群体是由负责在低频下发出的电子加速的冲击提供的。我们将模型应用于PKS 0637-752和PKS 1136-135的主要结的主要结的发射，这是两个最佳研究的对象。对于采用的一组基准参数，喷气功率不超过$ 10^{48} $ erg s $^{ - 1} $的限制值的限制值将磁场限制在$ 10 $ $ $ $ $ g以上，并指示中度横梁（$δ\ simeq 2 $）的PKS 0637-752。对于这两个来源，如果剪切层中的磁性湍流遵循Kolmogorov Spectrum，$ i（k）\ propto k^{ - q} $带有$ q = 5/3 $，但在剪切层的频谱之后，可以满足电子的加速度要比辐射冷却更快的要求，但是在Bohm like like case（$ q = 1 $）。
The nature of the intense X-ray emission from powerful extragalactic jets at large ($>1$ kpc) scale is still debated. The scenario that invokes the inverse Compton scattering of the CMB by electrons is challenged by the lack of gamma-ray emission in the GeV band. An alternative assumes synchrotron emission by a distinct population of ultra-high energy electrons. Here we present a concrete attempt to apply this scenario, exploring the specific model in which the ultra-high energy electrons are accelerated in a shear layer surrounding the jet. We limit the study to non-relativistic flows and particle acceleration is treated by a Fokker-Planck equation. The observed relation between low energy (radio, optical) and X-ray emission prompts us to assume that the required population of pre-accelerated particles is provided by a shock responsible for the acceleration of the electrons emitting at low frequencies. We apply the model to the emission of the principal knots of the jets of PKS 0637-752 and PKS 1136-135, two of the best studied objects. For the set of fiducial parameters adopted, the condition that the jet power does not exceeds a limiting value of $10^{48}$ erg s$^{-1}$ constrains the magnetic field above $10$ $μ$G and indicates moderate beaming ($δ\simeq 2$) for PKS 0637-752. For both sources, the requirement that acceleration of the electrons proceeds faster than radiative cooling can be met if the magnetic turbulence in the shear layer follows a Kolmogorov spectrum, $I(k)\propto k^{-q}$ with $q=5/3$, but cannot satisfied in the Bohm-like case ($q=1$).
