Prieto M Almudena, Brunetti Gianfranco, Mack Karl-Heinz
European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching, Germany.
Science. 2002 Oct 4;298(5591):193-5. doi: 10.1126/science.1075990.
Hot spots (HSs) are regions of enhanced radio emission produced by supersonic jets at the tip of the radio lobes of powerful radio sources. Obtained with the Very Large Telescope (VLT), images of the HSs in the radio galaxy 3C 445 show bright knots embedded in diffuse optical emission distributed along the post-shock region created by the impact of the jet into the intergalactic medium. The observations reported here confirm that relativistic electrons are accelerated by Fermi-I acceleration processes in HSs. Furthermore, both the diffuse emission tracing the rims of the front shock and the multiple knots demonstrate the presence of additional continuous re-acceleration processes of electrons (Fermi-II).
热点（HSs）是由强大射电源射电瓣尖端的超音速喷流产生的增强射电辐射区域。利用甚大望远镜（VLT）获得的射电星系3C 445中热点的图像显示，明亮的结嵌入在沿着喷流与星系际介质碰撞产生的激波后区域分布的弥漫光学辐射中。此处报告的观测结果证实，相对论电子在热点中通过费米-Ⅰ加速过程被加速。此外，追踪前激波边缘的弥漫辐射和多个结都表明存在电子的额外连续再加速过程（费米-Ⅱ）。
