COSMOS天区星系群中活动星系核比例的研究
发布时间：2018-11-26 18:46
【摘要】：活动星系核(Active Galactic Nuclei,简称AGN)是一类中央核区活动性很强的河外星系,其主要特征为核活动,能量来自与中心黑洞的物质吸积。AGN在星系形成和演化中扮演重要的角色。星系团是宇宙中最大的自引力束缚系统,是研究星系演化过程及其与环境相互作用的“实验室”。对星系团内AGN的统计研究可以在团内星系中心的超大质量黑洞的生长、AGN的供燃(fueling)机制、以及AGN对团内介质(Intra-Cluster Media,简称ICM)的长期影响等方面给出重要的线索。COSMOS巡天是哈勃空间望远镜巡天中一个重要观测计划,覆盖了赤道附近两平方度的天区。本文主要利用COSMOS深场中星系群及其成员星系样本,结合被光谱证认的X射线选AGN样本,研究星系群中AGN比例随红移演化问题。我们采用的X射线选AGN样本来自Brusa et al. (2010),其中的AGN满足X射线流量限制,并已经被光学光谱所确认。根据AGN吸积过程演化模型,这一类AGN可能尚处于黑洞显著增长的高吸积率演化阶段,因而具有明显的光学发射线特征。本文采用的星系群样本来自George et al. (2011)的X射线选星系群样本,包含了211个z1的X射线选星系群,其成员星系满足F814W24.2,且在3a显著度水平上在磁波段被探测到。我们将AGN样本和X射线选星系群样本进行交叉证认,只在其中的26个星系群中发现了27个AGN,其中绝大部分(96%)是窄线AGN。计算这26个群的AGN占比fAGN,发现其随红移有非常微弱的上升趋势,其线性相关系数很低。我们还对所有211个z1的星系群的成员星系按红移间隔Δz=0.1进行进行计数,发现AGN比例普遍低于1%,随红移的上升趋势变得更加微弱。此外,如果将星系群成员样本按照z0.5和z0.5两个区间进行计数,其AGN比例随红移上升的趋势更加显著。作为对比,我们还研究了场中的AGN比例随红移的变化,发现与群中AGN比例的变化趋势基本一致,说明星系群环境似乎对这类AGN的探测概率没有明显的影响。
[Abstract]:Active Galactic Nucleus (Active Galactic Nuclei,) is a class of extragalactic galaxies with strong activity in the central nuclear region. Its main feature is nuclear activity, and the energy comes from the accretion of matter from the central black hole. AGN plays an important role in the formation and evolution of galaxies. The cluster of galaxies is the largest self-gravitational binding system in the universe and is a "laboratory" for studying the evolution of galaxies and their interaction with the environment. The statistical study of AGN in clusters can be used to study the growth of supermassive black holes in the center of galaxies in clusters, the mechanism of AGN's fuel supply (fueling), and the effect of AGN on intracluster media (Intra-Cluster Media,). COSMOS survey is an important observation program of Hubble Space Telescope, covering two square degrees near the equator. In this paper, we mainly study the evolution of AGN ratio with redshift in COSMOS deep field galactic cluster and its member galaxy samples, combined with X-ray selected AGN samples identified by spectrum. The X-ray AGN samples we used came from Brusa et al.. (2010), in which the AGN satisfies the X-ray flow limit and has been confirmed by optical spectroscopy. According to the AGN accretion evolution model, this kind of AGN may still be in the stage of high accretion rate evolution of black hole, so it has obvious optical emission line characteristics. The sample of the galaxy cluster used in this paper is from George et al.. The (2011) sample of X-ray selected galaxies consists of 211 z1 clusters of X-ray selected galaxies, whose member galaxies meet F814W 24.2and are detected in the magnetic band at the level of 3a saliency. We cross-identified the AGN sample and the X-ray selected galaxy cluster sample, and found only 27 AGN, out of 26 of them, the vast majority (96%) of which were narrow-line AGN.. The AGN ratio fAGN, of these 26 groups is found to have a very weak upward trend with the redshift, and its linear correlation coefficient is very low. We also count the member galaxies of all 211 z1 clusters according to the redshift interval 螖 z0. 1. We find that the AGN ratio is generally lower than 1, and becomes weaker with the redshift rising trend. In addition, if we count the cluster members according to z0.5 and z0.5, the AGN ratio increases with the redshift. As a contrast, we also study the variation of AGN ratio with redshift in the field. It is found that the variation trend of the AGN ratio in the cluster is basically consistent with that in the cluster, indicating that the cluster environment does not seem to have a significant effect on the detection probability of this kind of AGN.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P157.6
[Abstract]:Active Galactic Nucleus (Active Galactic Nuclei,) is a class of extragalactic galaxies with strong activity in the central nuclear region. Its main feature is nuclear activity, and the energy comes from the accretion of matter from the central black hole. AGN plays an important role in the formation and evolution of galaxies. The cluster of galaxies is the largest self-gravitational binding system in the universe and is a "laboratory" for studying the evolution of galaxies and their interaction with the environment. The statistical study of AGN in clusters can be used to study the growth of supermassive black holes in the center of galaxies in clusters, the mechanism of AGN's fuel supply (fueling), and the effect of AGN on intracluster media (Intra-Cluster Media,). COSMOS survey is an important observation program of Hubble Space Telescope, covering two square degrees near the equator. In this paper, we mainly study the evolution of AGN ratio with redshift in COSMOS deep field galactic cluster and its member galaxy samples, combined with X-ray selected AGN samples identified by spectrum. The X-ray AGN samples we used came from Brusa et al.. (2010), in which the AGN satisfies the X-ray flow limit and has been confirmed by optical spectroscopy. According to the AGN accretion evolution model, this kind of AGN may still be in the stage of high accretion rate evolution of black hole, so it has obvious optical emission line characteristics. The sample of the galaxy cluster used in this paper is from George et al.. The (2011) sample of X-ray selected galaxies consists of 211 z1 clusters of X-ray selected galaxies, whose member galaxies meet F814W 24.2and are detected in the magnetic band at the level of 3a saliency. We cross-identified the AGN sample and the X-ray selected galaxy cluster sample, and found only 27 AGN, out of 26 of them, the vast majority (96%) of which were narrow-line AGN.. The AGN ratio fAGN, of these 26 groups is found to have a very weak upward trend with the redshift, and its linear correlation coefficient is very low. We also count the member galaxies of all 211 z1 clusters according to the redshift interval 螖 z0. 1. We find that the AGN ratio is generally lower than 1, and becomes weaker with the redshift rising trend. In addition, if we count the cluster members according to z0.5 and z0.5, the AGN ratio increases with the redshift. As a contrast, we also study the variation of AGN ratio with redshift in the field. It is found that the variation trend of the AGN ratio in the cluster is basically consistent with that in the cluster, indicating that the cluster environment does not seem to have a significant effect on the detection probability of this kind of AGN.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P157.6
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