| 题名 | Blazar 3C 345的MeV/GeV射线辐射机制研究 |
| 作者 | 王洪涛 |
| 学位类别 | 硕士 |
| 答辩日期 | 2007-06-13 |
| 授予单位 | 中国科学院研究生院（云南天文台） |
| 授予地点 | 北京 |
| 导师 | 白金明 |
| 关键词 | 活动星系核 耀变体 伽玛射线 辐射机制 理论模型 |
| 其他题名 | Research on MeV/GeV Gamma-Ray Emission Mechanism in Blazar 3C 345 |
| 学位专业 | 天体物理 |
| 中文摘要 | 活动星系核自上世纪40年代被发现以来就以其快速光变，高光度，高红移等极端特性成为天体物理最活跃的研究领域之一, 与这些特性相关的高效产能、辐射机制、空间分布和极端条件等成为竞相追逐的研究热点。这些问题的研究将揭示活动星系核的起源、结构和演化等未解之谜。 Blazar是活动星系核的一个子类，它是喷流沿视线夹角很小的一类活动星系核，它的一系列独特性质如高光度，快速光变和视超光速运动等都认为起源于相对论喷流，因此对blazar的研究就是对喷流的研究。通过对blazar以及其它射电噪活动星系核的研究将有助于最终解决喷流从黑洞吸积系统提取能量的物理机制。 上世纪90年代，康普顿伽玛射线天文台(CGRO)的发射成功为blazar的研究开辟了一个新的研究领域，CGRO在服役期间共探测到了66个高置信度的blazar以及27个可能的blazar，它们的能谱大多呈现双峰结构，对此的解释一般认为低能峰来源于相对论电子的同步辐射，而高能峰可能为同步自康普顿(SSC), 也可能是外康普顿(ERC)，外康普顿的种子光子可能来源于吸积盘、宽线区、尘埃环等，此外还有可能是强子产生的，目前尚无定论。将于今年8月份升空的另一高能伽玛射线望远镜-GLAST与EGRET相比探测能力有了大大的提高，有可能对blazar喷流的研究获得突破性进展。因此在未来几十年这一领域有着广阔的发展前景。 全文共分四章，第一章主要介绍活动星系核的基本性质及其分类，并简单介绍了活动星系核标准模型的发展史以及对标准模型最近的研究情况；第二章主要介绍blazar的几个著名的巡天样本及blazar的相对论喷流模型，以及相对论喷流模型的一些性质；第三章主要介绍了blazar在全波段能谱分布的特征以及在高能波段辐射模型的解释；并对两类特殊的blazar-MeV blazar和GeV blazar作了简要的介绍；第四章是我们近期已经发表的一项研究工作。EGRET源的辐射机制是一个非常值得研究的课题，但是历史上一些研究的非常多的天体(如：3C 345)EGRET却没有探测到它们的伽玛射线辐射，这样通过对这些非EGRET源与EGRET源的比较分析，从侧面也说明了EGRET源辐射机制的特性。我们的工作正是以此为出发点，主要从光变幅度，光学最小光变时标及时间延迟三个方面对3C 345、3C 273和3C 279作了一系列的比较分析，发现3C 345的伽玛辐射能谱可能与3C 273相似，即伽玛辐射的能谱峰在MeV能区，GeV能区的谱较陡，很可能正是此因EGRET在服役期间没有探测到3C 345。 |
| 英文摘要 | Since 1940s the AGN have been found, it is one of the most popular field in astrophysics for its violent variability, high lunminosity, high redshift and other extreme characteristics, high efficient produce energy, radiation mechanism, distribution in space and extreme condition become one of the most popular researching field in astrophysics field. The research about these problem will help to imply the origin,configuration and evolvement of AGN. Blazar is asubclass of AGN.According to unified model,it is a kind of AGN which the angle between the jet and the line of our sight is very small. Usually, its high luminosity, rapid variability and superluminal motion are come from relativistic jet, so the researching about blazar means the research about the jet, Through the researching about blazar and the other radio loud AGN is useful to solve the problem that jet obtain energy from the black hole and accretion system. Since the Compton Gamma-Ray Observatory was launched successfully in 1990s, It had opened a new researching field. It had detected 66 blazars with high confidence and 27 possible blazars. Their SED usually have "two bumps", The peak of low energy is usually considered as synchrotron radiation of the relativistic electron, and the peak of high energy usually considered as synchrotron-self-compton, external compton radiation whose seed photons may be come from accretion disk, broad line region, torus and so on. It also may be produced by hadron, there are no conclusion from now on. The second gamma-ray telescope-GLAST will be launched in August this year, Its detected capability is higher than EGRET, may have breakthrough greatly in blazar field. So there may have great prospect in the next tens years. There are four chapters in this thesis, Chapter one introduce the fundamental characteristics and the classification of AGN, and introduce the history of unified model and researching situation about unified model; The chapter two mainly introduce some famous samples of blazar survey and relativistic jet model,and some characteristics of relativistic jet; Chapter three present the spectral energy distribution of blazar in multi-band and the explanation of high energy radiation model, and introduce two special blazar - MeV blazar and GeV blazar simply; Chapter four is our work which has been accepted recently. The emission radiation of EGRET objects is a very popular field, but EGRET did not detect the radiation of some famous objects (eg: 3C 345). It suggests the emission radiation of GeV/MeV blazar from other aspects by compare and analysis the EGRET blazar and non-EGRET blazar. Our work is mainly compares and analysis the variability amplitude,the shortest variability timescale and time delay among 3C 345,3C 273 and 3C 279.We find the the SED of 3C 345 in gamma-ray band may be similar with 3C 273, that means the peak of gamma-ray SED is mainly in MeV energy, and the spectrum in GeV energy band is much steeper, May be EGRET did not detect 3C 345 by this reason. |
| 语种 | 中文 |
| 学科主题 | 天文学 |
| 页码 | 85 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.ynao.ac.cn/handle/114a53/5076]  |
| 专题 | 云南天文台_高能天体物理研究组 |
| 推荐引用方式 GB/T 7714 | 王洪涛. Blazar 3C 345的MeV/GeV射线辐射机制研究[D]. 北京. 中国科学院研究生院（云南天文台）. 2007. |
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