【作者】 李怀珍；

【导师】 谢光中； 戴宏；

【作者基本信息】 云南大学 ， 理论物理， 2011， 博士

【摘要】 本文对活动星系核的基本特性及分类、统一模型等做了较为全面的综述,然后对blazar天体的光变以及产能机制做了综述。然后详细介绍了本人在攻读博士学位期间主要的研究工作。Blazar天体是最亮也是最活跃的高能活动星系核,它的辐射覆盖了从低能的射电波段直到高能γ射线的整个电磁波段,并且其辐射表现出复杂、快速、相互关联的大幅光变特性。光变是blazar天体一个非常重要的观测特征,并且blazar天体的周期性爆发是非常有意义的,这是因为光变分析是我们理解blazar天体的中心结构和产能过程一个非常有用的方法。光变能反映辐射区域内部物理特征和结构的变化,因此光变是研究blazar天体基本物理特性非常有效的方法。通过对blazar天体光变的分析我们能更好的理解blazar天体的辐射机制和基本物理性质,确定的周期光变能帮助我们理解其中心结构,并有助于我们得到blazar天体的中心辐射区域的物理参数,对其物理模型提出强烈的限制。为此我们对两个具体源的光变进行分析,并研究了它们的中心结构。对3C 279的光变周期进行分析。我们从相关文献中收集了3C 279射电22GHz、37GHz、光学R波段和X射线2-10keV的光变数据并分析,发现3C 279是一个非常活跃的天体,并存在准周期爆发现象。通过功率谱,Jurkevich和离散相关函数(DCF)三种不同的周期分析方法对其光变进行分析发现3C 279存在P=130.6±1.3天的光变周期。根据Rieger在2004年给的观测周期Pobs和物理周期Pp之间的关系以及我们所得到的结果,我们计算得到3C 279中喷流的进动周期大约是29.6年,这与Carrara等人通过对喷流不同成分模拟得到的30年的进动周期是完全一致的。这说明在3C 279中存在一个进动喷流,并且我们得到的大约130.6天的周期性光变很可能是由喷流的螺旋进动引起的。除了对3C 279的光变周期进行分析之外,我们还对活动星系核的另一个子类Seyfert星系的一个典型的源ⅢZw 2的光变特性进行分析。我们利用Metahovi射电天文台对ⅢZw 2的22 GHz和37 GHz的射电观测数据给出了它的历史光变曲线,分析显示ⅢZw 2是个非常活跃的天体,并存在非正弦的光变。我们利用Jurkevich方法、功率谱方法和离散相关函数法对Seyfert星系ⅢZw 2光变周期进行了定量的分析发现其在射电波段存在约5.14年的周期,这与Brunthaler等人通过定性分析得到的大约5年的周期相吻合。分析显示ⅢZw 2在射电波段的约5.14年的周期性光变最可能的起因是双黑洞系统中喷流的螺旋进动。Blazar天体是活动星系核中非常典型的一类,它的辐射从低能射电扩展到高能X射线和γ射线波段。它的全波段能谱分布(SED)反映了其多波段辐射特性。不同子类的blazar天体的SED的相似或差异都反映了彼此间存在着相似或不同的物理机制和限制条件。对不同blazar天体的子类之间的关系的研究有利于我们理解blazar天体的基本性质,因此对blazar天体SED的研究是非常重要而且有意义的。我们收集了54个Fermi blazar天体的光学,X射线和γ射线的观测数据,并通过这些数据分析了宽波段谱指数αoχ和α-χγ之间的关系,同时也分析了内禀复合谱指数αxox和αγxγ之间的关系。内禀复合谱指数αxox和αγxγ之间的关系显示平谱射电类星体和低能峰BL Lac天体遵循了一个连续的分布趋势,这与以前别人得到的结果是一致的：存在一个从平谱射电类星体到低能峰BL Lac天体的谱序列。然而,高能峰BL Lac天体遵循了一个不同与前两类blazar天体的一个谱趋势,这说明高能峰BL Lac天体的能谱分布与平谱射电源和低能峰BL Lac天体是不同的。即使这样,当我们同时考虑三类blazar天体的时候,复合谱指数αxox和αγxγ存在强相关,这说明他们之间有类似的物理过程,这为统一图景提供了新的证据。更多还原

【Abstract】 In this thesis, the basic properties, classification, uniform model of the active galactic nuclei (AGNs) have been reviewed. Then, we also discussed the variability and the radiation mechanism of blazars, and detailed present our research work during PhD.Blazars are the brightest and most variable high-energy sources among ac-tive galactic nuclei, and their nonthermal continuum emission from redio band extend up to X-ray and7-ray frequency, and they exhibit rapidly, large ampli-tude, and correlativity variability. Variability is one of the important obser-vational characteristics of blazars, and the periodicity of outbursts in blazars is particularly interesting, because variability analysis is one of the powerful methods in understanding their central engines and energy production pro-cesses. Therefore, we analyze the variability of two objects and research their central structure. We compiled and analyzed the variability data of 3C 279 at 22 GHz,37GHz, optical R band and X-ray band, and found it is an extremely active object with quasi-periodic outbreaks. A period of P= 130.6±1.3 days was consistently confirmed by three methods:the power-spectrum method, the discrete correlation function (DCF) method, and the Jurkevich method. Based on the relationship between observed period Pobs and the precession period Pp given by Rieger and our result, the precession period of jet in 3C 279 is Pp (?)29.6 yr, which is completely consistent with the precession period of jet of about 30 yr obtained by Carrara et al.. This suggests that there is a precession jet in 3C 279 and the variability period of about 130.6 days that we obtained is most likely caused by the helical motion of the jet.In addition to the variability analysis of 3C 279, we also researched the variability characteristics of Seyfert galaxiesⅢZw 2 which is the other sub-class of AGNs. We have presented the radio light curves of the Seyfert galaxiesⅢZw 2 at 22 and 37 GHz taken from the database of Metsahovi Radio Ob-servatory, and the light curves show great activity with very complicated non-sinusoidal variations. Period of Pobs= 5.14±0.19 yr was consistently identified by three methods:the Jurkevich method, the power spectrum intensity estima-tion method and the discrete correlation function method, which is consistent with the qualitative result obtained by Brunthaler et al. (2003). The variability period of about 5.14 yr inⅢZw 2 is caused most likely by the helical motion of the jet.Blazars are a typical subclass of AGNs and their spectral energy distribu-tions reflect the muliband radio property. The similar and different SEDs of different subclasses of blazars indicate that there are similar or different physies mechanism and limit condition. Searching the connection of different types of blazars would substantially promote our understanding about the fundamental nature of blazars. Therefore, the relationship among different types of blazars is very interesting. We compiled the optical, X-ray andγ-ray data for 54 Fermi blazars and studied the relationship between the broad band spectral index aox andαxγ, as well as the relationship between the intrinsic composite spectral indices axox andαγxγfor this sample. The relationship between axox andαγxγreveals that FSRQs and LBLs follow a continuous trend, which is consistent with previous results, whereas HBLs follow a separate distinct trend. Even so, a unified scheme is also revealed fromαxox-αγxγdiagram when all three subclasses of blazars are considered.更多还原