【摘要】：活動星系核(Active Galactic Nuclei,簡稱AGN)是一類中央核區(qū)活動性很強(qiáng)的河外星系,其主要特征為核活動,能量來自與中心黑洞的物質(zhì)吸積。AGN在星系形成和演化中扮演重要的角色。星系團(tuán)是宇宙中最大的自引力束縛系統(tǒng),是研究星系演化過程及其與環(huán)境相互作用的“實(shí)驗(yàn)室”。對星系團(tuán)內(nèi)AGN的統(tǒng)計研究可以在團(tuán)內(nèi)星系中心的超大質(zhì)量黑洞的生長、AGN的供燃(fueling)機(jī)制、以及AGN對團(tuán)內(nèi)介質(zhì)(Intra-Cluster Media,簡稱ICM)的長期影響等方面給出重要的線索。COSMOS巡天是哈勃空間望遠(yuǎn)鏡巡天中一個重要觀測計劃,覆蓋了赤道附近兩平方度的天區(qū)。本文主要利用COSMOS深場中星系群及其成員星系樣本,結(jié)合被光譜證認(rèn)的X射線選AGN樣本,研究星系群中AGN比例隨紅移演化問題。我們采用的X射線選AGN樣本來自Brusa et al. (2010),其中的AGN滿足X射線流量限制,并已經(jīng)被光學(xué)光譜所確認(rèn)。根據(jù)AGN吸積過程演化模型,這一類AGN可能尚處于黑洞顯著增長的高吸積率演化階段,因而具有明顯的光學(xué)發(fā)射線特征。本文采用的星系群樣本來自George et al. (2011)的X射線選星系群樣本,包含了211個z1的X射線選星系群,其成員星系滿足F814W24.2,且在3a顯著度水平上在磁波段被探測到。我們將AGN樣本和X射線選星系群樣本進(jìn)行交叉證認(rèn),只在其中的26個星系群中發(fā)現(xiàn)了27個AGN,其中絕大部分(96%)是窄線AGN。計算這26個群的AGN占比fAGN,發(fā)現(xiàn)其隨紅移有非常微弱的上升趨勢,其線性相關(guān)系數(shù)很低。我們還對所有211個z1的星系群的成員星系按紅移間隔Δz=0.1進(jìn)行進(jìn)行計數(shù),發(fā)現(xiàn)AGN比例普遍低于1%,隨紅移的上升趨勢變得更加微弱。此外,如果將星系群成員樣本按照z0.5和z0.5兩個區(qū)間進(jìn)行計數(shù),其AGN比例隨紅移上升的趨勢更加顯著。作為對比,我們還研究了場中的AGN比例隨紅移的變化,發(fā)現(xiàn)與群中AGN比例的變化趨勢基本一致,說明星系群環(huán)境似乎對這類AGN的探測概率沒有明顯的影響。
[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.
【學(xué)位授予單位】：南京師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P157.6

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