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活动星系核中喷流的多波段光变研究
其他题名Multi-wavelength variability research in jet of AGN
廖能惠
学位类型博士
导师白金明
2014-05-24
学位授予单位中国科学院研究生院(云南天文台)
学位授予地点北京
学位专业天体物理
关键词活动星系核 喷流 多波段光变 辐射机制
摘要半个世纪以来,活动星系核由于其特殊的观测特征一直是天体物理的主要热门研究领域之一。通过研究活动星系核,不仅可以得到天体物理研究中 重要的对象,超大质量黑洞,其周围物理环境的信息,还可以研究星系中心超大质量黑洞与寄主星系的共同演化从而更深刻的了解整个宇宙的演 化过程。喷流是天体物理中常见的观测现象,从太阳的日冕喷流到活动星系核的大尺度喷流都是重要的研究对象。基于其极端的物理条件,研究 喷流有助于验证已有物理模型和探索新的物理机制。喷流被认为与中心致密天体的吸积过程有着紧密的联系。与此同时,喷流是连接中心致密天体 与外部的星际介质的直接桥梁。研究喷流对研究两者都有着重要的帮助作用。本文主要的阐述对象是活动星系核中的喷流,大致分成两个部分。 本文第一部分是背景和相关研究进展的简单介绍。第一章阐述了活动星系核的基本特征,包括其观测特征,理论模型和研究意义。同时还简单的 叙述了喷流在天体物理中的研究意义。射电噪活动星系核被认为是具有喷流的活动星系核,第二章我首先讨论了射电噪活动星系核的分类。 由于相对论喷流模型长期以来成功的解释了射电噪活动星系核的观测特征,其次我阐述了相对论喷流模型在射电噪活动星系核的应用。然后我介绍 了最基本的喷流的辐射模型,单区各向同性的轻子模型的物理图像,着重讨论了观测对模型的物理参数的限制。强子模型被简单介绍并且与轻子模 型相比较。随后我阐述了活动星系核喷流领域研究的重要问题。由于$Fermi$望远镜对本领域的研究有着强有力的推动作用,在第二章的最后我叙述了 在$Fermi$时代活动星系核中的喷流的研究进展,包含$Fermi$/LAT在伽马射线波段的主要观测结果与其余波段相关研究进展,以及对不同种类的源 的研究进展。第三章介绍了$Fermi$/LAT的工作原理,基本性能和数据处理的方法。 第二部分阐述了我的三个工作。第一个工作中,我们对典型的Blazar,S5~0716+714进行了从射电到伽马射线的详尽的多波段分析。相比于强子模型, 其多波段的光变特性能更自然的被轻子模型所解释。与此同时我们并没有发现支持强子模型的证据,孤立的伽马射线爆发。这意味着轻子在Blazar的 能量耗散过程中起到重要的作用。我们进一步通过能谱拟合排除了单纯的同步加自康普顿模型。喷流外的软光子场,不管是宽线区还是热尘埃的辐射 对于解释S5~0716+714是必须的。这意味,对于不同Blazar子类,其外光子场的强度可能存在演化关系。第二个工作,我们分析了PKS~0507+17的极端 的快速大幅度伽马射线光变。通过对这个事件的分析,PKS~0507+17的伽马射线辐射被首次认证。大幅度的伽马射线光变被探测到,天平均的峰值流量 比前两年平均值高两个量级。两倍时约为2-3小时的极端现象被探测到,这暗示这个PKS~0507+17的伽马射线辐射区域在宽线区之内。加上越亮越蓝的 伽马射线谱演化,这些观测现象能被经典的FSRQ的光变模型所解释。最后一个工作,我们分析了BZB~1451+5201的伽马射线与光学光谱数据,发现该源 可能是目前最远的伽马射线BL~Lac天体。我们详细的研究了其多波段的性质,与近邻的同类型的源进行了比较,对理解Blazar演化和各个子类的联系起 到帮助作用。
其他摘要Active Galactic Nuclei (AGN) are characterized by the peculiar observational phenomenon and have been one of the hottest areas of astrophysical research for half a century. Investigating the properties of AGN can shed light on the environment surrounding the center massive black hole and help us understand the co-evolution between the center massive black hole and the host galaxy,which is the hint of the evolution of the universe. Jet is the common phenomenon in the universe. They can be found through the small solar corona jet to the large scale jet in AGN. Based on the extreme physical condition, researching the astronomical jet can help to investigate the existed physical models and explore the unknown physical mechanisms. Jets are thought to be likely related to the accretion process of the center compact object and are the bridge between the center compact object and the external interstellar medium. This thesis mainly focuses the jet in the AGN and contains two parts. The first part is focusing on introduction of the background of the research of the jet in AGN. In the first section, I describe the basic properties of the AGN, including the observational characters and theoretical models. Then I introduce astronomical jets in different types of celestial bodies。In the second section, the radio loud AGNs classification which is based on the observational characters in different wavelengths and the SED properties is described. Since the relativistic jet model is widely accepted, I list several evidences of the relativistic jet model by comparing with the observational phenomena. Then, the classic jet radiation model, single zone homogeneous leptonic model, is briefly introduced. I discuss the observational constraints to the radiation model parameters. The hadronic model is simply mentioned and compared with the leptonic model. The challenges for the research of the jet in AGN is introduced in Section 2.4. In the end of the second section, the research progress of the jet in AGN at the $Fermi$ era is specially introduced. Firstly, the main results of the $Fermi$/LAT observation are presented. Then the radio, optical, X-ray and VHE $\gamma$-ray instruments and research results are given. Then the progress of multi-wavelength observation on different class of Blazars are presented. In the third section, I introduce the operation principle, the basic properties and the data reduction process of the $Fermi$/LAT. In the second part of the thesis, three research works are presented. In the first work, we present the detailed analysis and results of long term simultaneous observations in the radio, near-infrared, optical, X-ray and $\gamma$-ray bands, together with our own photometric observations for S5~0716+714. Its multi-wavelength variability properties can be naturally explained by the classic leptonic blazar radiation models. The orphan $\gamma$-ray flare which strongly supports the hadronic models is not detected. Electrons probably play an important role in the energy dissipation of Blazars. Furthermore, different leptonic radiation models are distinguished. The pure SSC model is ruled out, while the external soft photons such as the broad line region or the hot dust emission, is needed to explain the $\gamma$-ray emission of S5~0716+714. The intensity of the external soft photon fields may exhibit a evolution behavior through different types of Blazars. In the our second study, we report a detailed analysis of $\gamma$-ray data of 2FGL J0509.9+1802, especially focusing on April 2013 when extraordinary $\gamma$-ray variability has been detected. The $\gamma$-ray emission of PKS 0507+17 is identified at the first time. The daily peak flux is over two orders of magnitude higher than the two-year average flux. Rapid $\gamma$-ray variability with doubling time of 2-3 hours has been detected, indicating a location of $\gamma$-ray emission inside the broad line region. Together with the bluer-when-brighter $\gamma$-ray spectr
学科领域天文学
页数131
语种中文
文献类型学位论文
条目标识符http://ir.ynao.ac.cn/handle/114a53/5570
专题丽江天文观测站(南方基地)
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GB/T 7714
廖能惠. 活动星系核中喷流的多波段光变研究[D]. 北京. 中国科学院研究生院(云南天文台),2014.
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