天鹅座A和类似的FR II经典双射电源中气体和宇宙射线的自洽演化
Self-consistent evolution of gas and cosmic rays in Cygnus A and similar FR II classic double radio sources
摘要：
在天鹅座A和其他经典的FR II双射电源中，来自以晕为中心的星系核心的强大的反向喷流进入周围的星系团气体，在喷流末端形成受冲击和压缩的星系团气体热点。移动的热点夹在两个冲击之间。一个面向内部的激波接收来自喷流的动量和宇宙射线，并产生额外的宇宙射线，这些宇宙射线形成一个沿喷流轴延伸的射电瓣。一个向外的弓形激波直接进入未受干扰的气体群或气体簇，形成一个包围射电瓣的激波气体茧。我们描述的计算，遵循自洽的动力学演化的冲击集群气体和相对论性同步辐射气体内的叶片。相对论和非相对论分量通过与具有动态可忽略的能量密度的小磁场相互作用来交换动量。天鹅座A的演化几乎完全由来自热点的宇宙射线能量控制。从喷流流入热点的质量被认为是小的，大大减少了沿着喷流流回的气体质量，这在以前的计算中很常见，这将破坏FR II射电瓣内观察到的同步加速器损失年龄的空间分离。我们计算了当热点的速度和宇宙线亮度恒定以及它们随时间变化时茧的演化。如果宇宙射线在流入射电瓣之前与热点中的星系团气体混合，热气体就会被加热到温和的相对论温度，从而在瓣内产生无法观察到的压力。
英文摘要：
In Cygnus A and other classical FR II double radio sources, powerful opposing jets from the cores of halo-centered galaxies drive out into the surrounding cluster gas, forming hotspots of shocked and compressed cluster gas at the jet extremities. The moving hotspots are sandwiched between two shocks. An inner-facing shock receives momentum and cosmic rays from the jet and creates additional cosmic rays that form a radio lobe elongated along the jet axis. An outer-facing bow shock moves directly into the undisturbed group or cluster gas, creating a cocoon of shocked gas enclosing the radio lobe. We describe computations that follow the self-consistent dynamical evolution of the shocked cluster gas and the relativistic synchrotron-emitting gas inside the lobes. Relativistic and non-relativistic components exchange momentum by interacting with small magnetic fields having dynamically negligible energy densities. The evolution of Cygnus A is governed almost entirely by cosmic ray energy flowing from the hotspots. Mass flowing into hotspots from the jets is assumed to be small, greatly reducing the mass of gas flowing back along the jet, common in previous calculations, that would disrupt the spatial segregation of synchrotron-loss ages observed inside FR II radio lobes. We compute the evolution of the cocoon when the velocity and cosmic ray luminosity of the hotspots are constant and when they vary with time. If cosmic rays mix with cluster gas in hotspots before flowing into the radio lobe, the thermal gas is heated to mildly relativistic temperatures, producing an unobserved pressure inside the lobe.
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