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Blazar中喷流的多波段辐射研究
陈亮
学位类型博士
导师白金明
2010-05-27
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 耀变体 辐射机制
摘要活动星系(核)因其剧烈的活动现象、极端的物理条件而赢得了广大天文学家和(天体)物理学家的青睐。对活动星系核的研究必将加深我们对于宇宙的演化、黑洞的形成和增长、星系的形成和演化的认识;而它给我们直接带来的将是对极端条件下的物理过程的理解,比如强引力场下物质/能量的转化、转移过程。作为活动星系核的一个结构,喷流又以其极端之极端的物理条件让人觉得匪夷所思而又充满诱惑--巨大能量载体以接近光速运动而又能保持其准直。对它的研究将帮助我们揭开黑洞物理的神秘面纱、帮助我们理解不同尺度的相互关联(从黑洞到星系)、星系和宇宙的演化等等;对其本身的研究又将推动我们对基础物理的认识进程--磁化等离子体的物理过程。 本文首先介绍了AGN及其物理结构。第二章中,我们首先讨论电磁波在传播过程中的辐射转移。在介绍完不同AGN中的喷流之后;主要从能谱、光变、空间结构和偏振四个方面相对详细地介绍AGN中喷流的观测现象;而后又进一步引出相对论喷流模型。在总结观测现象和不同活动星系核中喷流的时候,我们从几何效应和物理本质两个方面来讨论统一模型。之后,我们引出从观测现象到喷流物理的桥梁--能量转移和辐射机制;在此我们将谈到喷流物理研究的三个方面/层面的内容:喷流能量的耗散、喷流能量的输运以及喷流的产生问题。重点将集中在喷流的辐射问题上。于是,我们便进入了第三章:关于辐射机制(轻子模型)的相对详细的讨论。 以上内容为本文的综述部分,主要是讨论本领域的研究现状及存在的问题。在此基础上,本论文将介绍我们的一点研究工作。第一个是关于Blazar的伽玛射线辐射机制的问题。我们给出了从多波段能谱来限制辐射机制的方法:若是外康普顿(EC)主导,峰值频率、光度需遵循LIC/Lsy∝νIC/νsy2;若是同步自康普顿主导,辐射区尺度需有一个下限。我们又使用这种方法对Fermi亮AGN进行检验,发现大部分源可能是EC主导。第二个工作是对Blazar序列的检验。我们仍使用Fermi亮AGN,发现在原来序列的基础上多出一些低峰频低光度的源。而这种对观测Blazar序列的偏离却可以在“理论”Blazar序列下得到解释:即更高的光子场密度将更快地冷却电子,从而有更低的峰值电子能量。我们另外研究了非射电噪活动星系核III Zw 2的喷流的辐射。发现其喷流的功率与已知的伽玛射线Blazar的喷流的功率相当,并遵循相同的能量转化率;同时我们预言它的伽玛射线辐射有可能被Fermi/LAT探测到,而现在Fermi十一个月的样本中没有它,这可能是由于现在不是爆发态的原因。我们同时指出对非射电噪AGN喷流的研究可能指引我们更好的理解喷流的演化、成长问题。 随着望远镜发展和理论技术的进步,本领域研究正蒸蒸日上;这些只能在最后一章以前景展望的形式给出:机遇与挑战并存!
其他摘要For the reason of violent activities and extremely physical conditions, numerous astronomers and astrophysicists are attracted to conduct the researches on active galactic nuclei (AGNs). The studies certainly will improve our understanding of the cosmological evolution, the growth of black hole, the production and evolution of galaxies. This will also expands our knowledge on the physical processes with extreme conditions, for example, the process of energy transformation with strong gravity. The jet in AGN even has its inconceivable but charmed properties: a huge energy carrier moving with relativistic velocity and collimation to large distance. The studies on jet will unveil the physical processes around the black hole, the relationship between the central black hole and its host galaxy, and the most basic physics: the processes in magnetized plasma. In this thesis, we firstly introduce the general properties and the structure of AGN (Chapter 1). In the Chapter 2, we give the generally phenomenological properties of jet and the contents of the research on jet. The first part includes that, 1) the radiative transfer at the space from ANG to earth, 2) jet in different AGNs, 3) the spectra energy distribution (SED) of jet emission, 4) the variability of jet emission, 5) the space structure of jet, 6) the polarization, 7) the relativistic effect on jet emission, 8) the unified model. The second part includes the energy dissipation, the energy spread, and the production of jet. To discuss those aspects, we mainly focus on the point of radiation -- the bridge connecting the phenomenon and jet physics. Therefore, we discuss relative more detail on the radiative processes of jet emission in the Chapter 3. All above aspects are our summary, aiming at pointing out the present status and the problems in this field. Our research articles are listed in Chapters 4-6. The first one is that we give a method to determine which of external Compton (EC) or synchrotron self Compton (SSC) will dominate the $\gamma$-ray emission in Blazar. The results are, 1) that if the EC dominates the $\gamma$-ray emission, the luminosity and frequencies follow LIC/Lsy∝νIC/νsy2. 2) that if the SSC dominates the $\gamma$-ray emission, the size of the emission region has a low limit. We then use the method to test the Fermi bright AGNs, and find that most sources may have EC dominating the $\gamma$-ray emission. The second work is that we use the Fermi bright AGNs to test the blazar sequence. We find many blazars with low luminosity and low peak frequency, which is unexpected in phenomenological blazar sequence. While this contradictory can be explained within the "theoretical blazar sequence". Chapter 6 shows our study on non-radio loud AGN III Zw 2. We find that the jet in this source has similar jet power at that in $\gamma$-ray blazars. We also predict that the $\gamma$-ray emission from this source can be detected by Femri/LAT. While III Zw 2 is not included in the first catalog of Fermi/LAT AGNs. This may be the reason of that III Zw 2 is in its low state. We also argue that the studies on the jet in non-radio loud AGNs will improve our understanding on the growth and evolution of jet. The research on jet is now in its ascendant. This will be discussed in our last Chapter: Opportunities and Challenges!
学科领域天文学
页数128
语种中文
文献类型学位论文
条目标识符http://ir.ynao.ac.cn/handle/114a53/5560
专题丽江天文观测站(南方基地)
推荐引用方式
GB/T 7714
陈亮. Blazar中喷流的多波段辐射研究[D]. 北京. 中国科学院研究生院(云南天文台),2010.
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