Jet Radiation Properties of 4C 49.22: from the Core to Large-scale Knots
Jet Radiation Properties of 4C 49.22: from the Core to Large-scale Knots
复制标题
4C 49.22 的射流辐射特性：从核心到大型结
DOI：
10.3847/1538-4357/aadd0b
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发表时间：
2018
影响因子：
4.9
通讯作者：
Liang En-Wei
中科院分区：
文献类型：
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作者：
Zhang Jin;Zhang Hai-Ming;Yao Su;Guo Sheng-Chu;Lu Rui-Jing;Liang En-Wei
4C +49.22是一个γ射线平谱射电类星体，具有明亮而复杂的喷流。我们调查的核心和大规模的结的性质，通过使用它们的光谱能量分布（SED）。对4C +49.22过去8年的Fermi/LAT数据的分析表明，除了明亮的爆发外，还存在长期稳定的γ射线发射成分。对于核区，用单带轻子模型解释了γ射线发射和低能带同时发射的现象。随着γ射线通量的衰减，导出的射电核心喷流的磁化参数和辐射效率降低，可能表明大部分磁能在秒差距尺度上转换为粒子的动能。对于大尺度的纽结，通过考虑宇宙微波背景光子的逆康普顿散射，可以用轻子模型再现它们的射电-光学-X射线SEDs。这些结的预测γ射线通量之和与LAT在1024 Hz处观测到的稳定γ射线分量相当，表明稳定γ射线发射可能部分由这些大尺度结贡献。这可能会掩盖来自无线电核心的低水平γ射线发射的通量变化。推导出的结的体洛伦兹因子随着距核心距离的增加而减小，说明了喷流在很大程度上的减速。核心和结的功率大致相同，但喷流从核心区域的高度磁化变为大规模结中的粒子主导。
4C +49.22 is a γ-ray flat-spectrum radio quasar with a bright and knotty jet. We investigate the properties of the core and large-scale knots by using their spectral energy distributions (SEDs). Analysis of the Fermi/LAT data from 4C +49.22 over the past eight years reveals a long-term steady γ-ray emission component besides bright outbursts. For the core region, the γ-ray emission together with the simultaneous emission in the low-energy bands at different epochs is explained with the single-zone leptonic model. The derived magnetization parameters and radiation efficiencies of the radio-core jet decrease as the γ-ray flux decays, likely indicating that a large part of the magnetic energy is converted to the kinetic energy of particles on a parsec scale. For the large-scale knots, their radio–optical–X-ray SEDs can be reproduced with the leptonic model by considering the inverse Compton scattering of cosmic microwave background photons. The sum of the predicted γ-ray fluxes of these knots is comparable to that observed with LAT at ∼1024 Hz of the steady γ-ray component, indicating that the steady γ-ray emission may be partially contributed by these large-scale knots. This may conceal the flux variations of the low-level γ-ray emission from the radio core. The derived bulk Lorentz factors of the knots decrease with increasing distance from the core, illustrating the deceleration of the jet on a large scale. The powers of the core and knots are roughly of the same order, but the jet changes from highly magnetized in the core region to particle-dominated in the large-scale knots.