邻近并合星系中的AGN频度与活动性的研究
文献类型：学位论文
| 作者 | 秦龙华
|
| 学位类别 | 硕士 |
| 答辩日期 | 2011-05-31 |
| 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 | 邬文弢 |
| 关键词 | 目视审视 并合 样本 AGN 统计 |
| 其他题名 | The Frequency and Activity of AGN in the Local Merger |
| 学位专业 | 天体物理 |
| 中文摘要 | 在1926-1936年间，哈勃首次利用目视的方式对 星系形态进行分类，但人们随后发现了一些形态非常特殊的星系，不能归为哈勃的标准形态分类，比如一些星系有着长长的潮汐臂，并展示了很多不规则的轮廓，后来Toomre & Toomre 的星系并合理论揭示了上述很多星系是由星系间的并合产生的。 这样的并合星系在星系形成和演化过程中扮演了一个引人入胜的角色。有些并合星系也可能触发了活动星系核（AGN）现象。此外盘并合星系模型也暗示了并合对星系形态产生了不可逆的改变。在一数类受广泛关注的特殊星系诸如玛卡良星系、红外亮星系、以及类星体的寄主星系中，都能发现并合星系的存在。对远距离星系成像也反映出星系相互作用以及后来的星系并合也是B－O效应（Butcher-Oemler effect）产生的一种机制。 由于在星系相互作用及演化中尚缺乏一个完备的星系并合样本，因此基于这个目的，导师在本人的协作下利用斯隆（SDSS)所提供的高质量图像，可以用来研究互相作用星系的形态细节。我们利用计算机来进行图像的拼接合成以提高信噪比，从而使导师很好的证认出了一个邻近的并合星系样本。 在得到的完备性并合星系样本的基础上我在导师的帮助下进行了并合星系中AGN频度与活动性的研究。在并合星系与一般性星系的AGN 的频度方面我发现以下统计特征：对于赛弗特星系、LINERs星系以及星爆星系的频度在并合星系比一般性星系中的频度提高了两倍。然而对于其活动性，赛弗特星系、LINERs星系的活动性没有被显著增强。对AGN活动性的统计中，基于AGN核的很大部分能量以X射线辐射出的这一预期，我下载XMM-Newton卫星获得的邻近星系X射线数据，经行了AGN活动性的统计研究，得出并合并没有显著地提高赛佛特与LINER星系以及星爆星系的活动性。通过对以Mayer和Hopkins为代表的利用数值模拟对并合星系与星系中心黑洞的形成及核区活动性的研究结果进行分析，得出这些理论预言与我们统计的结果不符，从已有的星系恒星知识来考虑，本文研究结果提示应当考虑超星系风在并合过程中对气体的影响。 |
| 英文摘要 | During the years 1922-1936, Hubble studied the morphologies of thousands of nearby galaxies and proposed Hubble's Morphological Sequence. Later, people found some special morphology that can hardly be categorized into the standard Hubble's Sequence. Some galaxies have long tidal tails and showed irregular shapes. Finally, the model of TT (Toomre & Toomre 1972) pointed out that those of galaxies were produced by merging between galaxies. Merger galaxies have important roles in individual galaxy evolution and population of galaxies. Some merging processes may have triggered series of phenomena like starburst and Active Galactic Nuclei (AGN). In addition, modeling of disk-galaxy mergers suggests that morphological types of the participants can be irreversibly changed. Mergers do occur in widely considered peculiar-galaxy populations such as Markarian galaxies and ULIRGs, and even the hosts of QSOs. Images of distant galaxies have implicated strong interaction and subsequent mergers are among the mechanism of the Butcher-Oemler effect. For lacking a complete merger sample in study of interaction and evolution of galaxies, my adviser, under my help, has compiled a sample of mergers based on SDSS high-quality images. We used computer algorithms to coadd images for enhancing the signal-to noise-ratios (SNR), which enables my adviser to visually identify a complete sample of nearby mergers. Based on the obtained sample, with my adviser's help, I finished a study of frequencies and activities of AGN in the nearby mergers. In the result of statistic frequencies, I have found that, the frequencies of either Seyfert/LINER or starburst galaxies in mergers are about twice of those in normal galaxies. As for activities, there is evidence that merging has affected the Seyfert and LINER little. Under the common perception that in AGN, a substantial amount of energy is emitted by X-rays, I have downloaded the X-ray data of nearby galaxies from the XMM-Newton satellite, and carried out a study of AGN activities. The results show that merging enhances the Seyfert, LINER activities slightly if any. Through the analysis of Mayer and Hopkins's merging-galaxy simulation, I find out that my results do not fit their simulated result. From existing knowledge of galaxies and stars, my results suggest that the roles of super-galactic wind can not be ignored during the merging processes. |
| 学科主题 | 天文学 |
| 语种 | 中文 |
| 源URL | [http://ir.ynao.ac.cn/handle/114a53/5087]  |
| 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 | 秦龙华. 邻近并合星系中的AGN频度与活动性的研究[D]. 北京. 中国科学院研究生院（云南天文台）. 2011. |
入库方式： OAI收割
来源：云南天文台
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