Fermi/LAT observations of lobe-dominant radio galaxy 3C 207 and possible radiation region of γ-rays

作     者：Sheng-Chu Guo Hai-Ming Zhang Jin Zhang En-Wei Liang 

作者机构：Guangxi Key Laboratory for Relativistic Astrophysics Department of Physics Guangxi University Key Laboratory of Space Astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2018年第18卷第6期

页      面：93-98页

核心收录：

学科分类：0709[理学-地质学] 07[理学] 0708[理学-地球物理学] 070401[理学-天体物理] 0704[理学-天文学] 0825[工学-航空宇航科学与技术] 

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 11573034, 11533003, 11851304 and U1731239) the National Basic Research Program of China (973 program, 2014CB845800) support from special funding from the Guangxi Science Foundation for Guangxi Distinguished Professors (Bagui Yingcai & Bagui Xuezhe 2017AD22006) 

主　　题：galaxies: active galaxies: jets radiation mechanisms: non-thermal galaxies: individual(3C 207) 

摘      要：3 C 207 is a lobe-dominant radio galaxy with a one sided jet and bright knots, spanning a kpcMpc scale, which have been resolved in the radio, optical and X-ray bands. This target was confirmed as a γ-ray emitter with Fermi/LAT, but it is uncertain whether the γ-ray emission region is the core or knots due to the low spatial resolution of Fermi/LAT. We present an analysis of its Fermi/LAT data acquired during the past 9 years. Different from the radio and optical emission from the core, it is found that theγ-ray emission is steady without detection of flux variation at over a 2σ confidence level. This likely implies that the γ-ray emission is from its knots. We collect the radio, optical and X-ray data of knot-A,the closest knot from the core at 1.4′′, and compile its spectral energy distribution(SED). Although the single-zone synchrotron+SSC+IC/CMB model that assumes knot-A is at rest can reproduce the SED in the radio-optical-X-ray band, the predicted γ-ray flux is lower than the LAT observations and the derived magnetic field strength deviates from the equipartition condition by 3 orders of magnitude. Assuming that knot-A is moving relativistically, its SED from radio to γ-ray bands would be represented well with the single-zone synchrotron+SSC+IC/CMB model under the equipartition condition. These results likely suggest that the γ-ray emission may be from knot-A via the IC/CMB process and the knot should have relativistical motion. The jet power derived from our model parameters is also roughly consistent with the kinetic power estimated with radio data.