论文标题
Centaurus a kiloparsec射流中的物理条件和颗粒加速度
Physical Conditions and Particle Acceleration in the Kiloparsec Jet of Centaurus A
论文作者
论文摘要
Centaurus A千帕斯克级喷射的非热发射具有两个显着的特征，明亮的扩散发射和许多紧凑的结，这些结已经在X射线和无线电观测中进行了深入研究。 H.E.S.S.最近报道说，该物体的高能伽马射线发射沿着喷气方向延伸到核心的一公斤。在这里，我们结合了这些观察结果，以限制KPC-JET的物理条件并研究非热发射的起源。我们表明，漫射喷射是弱磁化（$η_b\ sim10^{ - 2} $），并且由热颗粒在能量上占主导地位。我们还表明结是放大磁场和粒子（重新）加速的位点。为了在热颗粒中保持足够的能量，打结区域中的磁性和非热粒子能量受到严格的约束。最合理的条件是它们之间的能量等级，$η_B\simη_e\ sim0.1 $。这种弱磁能意味着结中的颗粒处于缓慢的冷却状态。我们建议整个KPC规模的扩散发射可以由加速并从结中逸出的颗粒提供动力。
The non-thermal emission from the kiloparsec-scale jet of Centaurus A exhibits two notable features, bright diffuse emission and many compact knots, which have been intensively studied in X-ray and radio observations. H.E.S.S. recently reported that the very-high-energy gamma-ray emission from this object is extended along the jet direction beyond a kiloparsec from the core. Here, we combine these observations to constrain the physical conditions of the kpc-jet and study the origin of the non-thermal emission. We show that the diffuse jet is weakly magnetized ($η_B\sim10^{-2}$) and energetically dominated by thermal particles. We also show that knots are the sites of both amplified magnetic field and particle (re-)acceleration. To keep sufficient energy in thermal particles, the magnetic and non-thermal particle energy in the knot regions are tightly constrained. The most plausible condition is an energy equipartition between them, $η_B\simη_e\sim0.1$. Such weak magnetic energy implies that particles in the knots are in the slow cooling regime. We suggest that the entire kpc-scale diffuse emission could be powered by particles that are accelerated at and escaped from knots.
