深场中的高红移星系和活动星系

发布时间：2017-12-30 19:09

本文关键词：深场中的高红移星系和活动星系　出处：《中国科学技术大学》2012年博士论文　论文类型：学位论文

【摘要】：1999年发射升空的Chandra以其无与伦比的分辨率和低背景完成了大量的科学价值显著的深场观测.我的博士论文研究工作从系统分析Chandra深场数据开始,并对Chandra南天深场中两个特殊的具有相对论外流的高红移类星体进行了细致研究.由于Chandra X射线望远镜杰出的性能,这些深场的数据不仅对研究类星体和活动星系至关重要,同时也提供了研究高红移星系的崭新的技术手段.近年来人们通过窄波段测光的方法寻找到大量的高红移莱曼α发射线(LAE)星系,这些高红移LAE星系对我们了解高红移宇宙的性质以及早期宇宙中的星系形成与演化具有不可替代的作用.我们利用Chandra深场的X射线观测数据系统研究了高红移LAE星系的X射线观测性质,分析了LAE星系中的活动星系核(AGN)的贡献,从X射线数据获得了这些星系中恒星形成率的上限,并限定了Lyα在星系中的逃逸几率.随后我们将研究视野拓展到高红移LAE星系的光学观测与分析,包括光谱证认,光度函数,Lyα线等值宽度分布,成团性等方面. 在第一章,我简单介绍了X射线天文学的发展以及Chandra X射线深场,以及宇宙的恒星形成历史和搜寻高红移恒星形成星系的方法. 在第二章,我们给出了LALA Cetus天区基于Chandra X射线卫星174千秒的曝光数据的X射线源星表.这里我们介绍了如何一步步处理Chandra成像观测并得到最终星表和分析的结果,并在该天区发展使用了一种分析X射线背景的新方法. Chandra南天深场具有累计4Ms的有效曝光时间,是人类所获得的最深的X射线观测.我们在第三章中处理分析了Chandra对CDF-S的观测数据.之前的研究使用CDF-S最早的1Ms的观测数据探测到了两个具有相对性外流特征的高红移类星体.我们对随后的1Ms Chandra数据分析进一步验证了之前的观测结果,这种后续重复观测的验证对于天文学中发现的罕见观测特征的研究不可缺少(从大量天文数据中探测到纯粹的高显著水平的背景噪声涨落的可能性往往不可忽略),从而彻底排除了这些观测特征来源于背景噪声的可能性.我们的分析还表明其中一个类星体的外流可能存在外流速度的减弱或者电离态的变化. 第四章,我们转而研究星系的x射线辐射特征.我们的星系样本是窄波段巡天找到的红移4.5的莱曼α发射线星系.我们发现除去一个源有强烈的x射线辐射,而且已被光谱证认为红移4.48的一型类星体,其它的源都没有x射线辐射,即使用叠加X射线光子的方法也没有探测到信号.我们得到红移4.5的莱曼α发射线星系的x射线辐射的平均(3σ)上限,为L0.5-2keV2.4×1042erg s-1分析已有x射线探测的红移z2的莱曼α发射线星系,我们发现它们都是AGN,但Lyα等值宽度都小于200A.具体分析1型AGN模版和典型2型AGN,我们发现样本里隐藏的AGN比例会非常小,而且大都是在小等值宽度的子样本里. 第五章里,我们延续了第四章的方法,对CDF-S天区所有的莱曼α发射线星系样本的x射线性质进行分析,包括红移z-0.3,1.0,2.1,3.1,3.2,4.5,5.7和6.5的莱曼α发射线星系样本.我们发现仅红移0.3处有x射线探测,对应x射线辐射是来自于恒星形成过程,更高红移处,只能得到x射线辐射的上限.我们假定此类星系的x射线辐射都是来自于恒星形成过程,因为x射线对星系里的尘埃不敏感,故而由x射线得到的恒星形成率和由Lyα得到的恒星形成率之比可以用来限制Lyα光子在星系里的逃逸比例.我们的结果和用其它方法得到的一致.我们发现,红移2-3处,Lyα光子在星系里的逃逸比例fLyαcsc14%(置信度84%).我们的数据在99.87%的置信度上排除了fLyαcsc5.7%. 接下来我们转移到莱曼α星系的光学性质.第六到八章里,我们基于红移4.5的莱曼α星系样本的光谱证认观测,分别讨论了莱曼a光度函数,莱曼α等值宽度分布,以及莱曼α星系的成团性.在第六章光度函数的分析里,我们综合了所有红移4.5处的莱曼a星系的光度函数,并和其它红移处的光度函数进行比较.我们发现莱曼α星系的光度函数存在演化,而且积分莱曼α星系的光度函数所得到的莱曼α光子的密度在整个宇宙学阶段同UV波段选的恒星形成星系一致,意味着宇宙尺度上莱曼α光子逃逸的比例是恒定的.第七章等值宽度分布里,我们用波段比代替直接计算等值宽度,发展出蒙特卡罗方法对等值宽度和线光度的依赖关系进行比较分析,发现等值宽度遵从指数分布且不依赖于线的强度.我们的蒙特卡罗方法有助于对未来窄波段巡天的设计.第八章,我们分析了光谱证认后的星系的成团性,肯定了以前仅基于测光选样本的成团性的结论.我们发现莱曼α光度大的子样本并没有表现出大的成团性,这与以前的结论不同.
[Abstract]:1999 launch of the Chandra with its incomparable resolution and low background finished deep field observation the scientific value significantly. My dissertation research from the system analysis of Chandra data and the deep field, Chandra Southern Deep Field in two with special relativistic high redshift quasars outflow was studied in detail the performance of Chandra. X ray telescope outstanding, these deep field data not only on quasars and active galaxies is essential, but also provides a new research high redshift Galaxy Technology. In recent years people through the method of narrow band photometry to find a large number of high redshift Lehmann alpha emission line galaxies (LAE). These high redshift galaxies LAE to our understanding of the high redshift universe and the nature of the early universe galaxy formation has irreplaceable function and evolution. We use the Chandra depth of field X ray observation data of X ray observation properties of high redshift Galaxy LAE, analysis of the LAE Galaxy in the active galactic nuclei (AGN) contribution from X ray data obtained by the star formation rate limit, and defines Ly alpha in the galaxy in the escape probability. We then extend the scope of research to the optical observation and analysis of high redshift Galaxy LAE, including spectral identification, luminosity function, distribution of equivalent width Ly alpha line, into the group and so on.
In the first chapter, I briefly introduce the development of X ray astronomy, the Chandra X ray deep field, the history of the star formation in the universe, and the search for high redshift star forming galaxies.
In the second chapter, we give the LALA Cetus area Chandra X ray exposure data based on satellite 174 thousand seconds X X-ray source catalog. Here we introduce a step by step how to deal with Chandra imaging observation and get the final catalogue and the results of the analysis, and in the area of development using a new method to analyze X ray background.
Chandra Southern deep field has accumulated exposure time of 4Ms, is achieved by man's deepest X ray observation. We analyzed the observation data of CDF-S Chandra in the third chapter. The observation data before the earliest research using CDF-S 1Ms was detected in two with high redshift quasars relative outflow characteristic analysis of 1Ms Chandra data. We then further verify the observational results before the validation of this follow-up of repeated measurements for rare observational features found in the study of Astronomy (an astronomical data from a large number of detected probability of background noise fluctuation high significant level of pure often can not be ignored), and thus the possibility of completely exclude these observational features from background noise. Our analysis also shows that one of the quasar outflows possible outflow rate weakened or electric The change of off state.
The fourth chapter, we turn to study the X radiation characteristics of galaxies. Our galaxy sample is a narrow band survey found a redshift of 4.5 Lehmann alpha emission line galaxies. We found that despite a strong source of X radiation, and has been a type of quasars as a redshift of 4.48, other sources are not X radiation, method using superposition of X ray photons have no detectable signal. We obtain the average X ray redshift 4.5 Lehmann alpha emission line galaxies radiation (3 sigma) limit, the existing X ray detection redshift Z2 Lehmann alpha emission line galaxies is L0.5-2keV2.4 * 1042erg S-1 analysis, we found that they are is AGN, but the Ly alpha equivalent width is less than 200A. specific analysis of type 1 AGN template and typical type 2 AGN, we found the hidden AGN in the proportion of sample is very small, and most of them are small in the equivalent width of sub sample.
In the fifth chapter, we extend the method in the fourth chapter, on the nature of the CDF-S area X ray all the Lehmann alpha emission line Galaxy samples were analyzed, including red z-0.3,1.0,2.1,3.1,3.2,4.5,5.7 and 6.5 Lehmann alpha emission line galaxies. We found only 0.3 at redshift X ray detector, corresponding to X radiation from the star formation the process, more high redshift, only x radiation limit. X ray radiation we assumed that such galaxies are from the star formation process, because the X ray is not sensitive to the galaxies in the dust, it is given by the X ray of the star formation rate and obtained by Ly alpha star formation rate can be used to Ly alpha photons in the galaxies in the escape ratio. Our results are consistent with that obtained by other methods. We found that the red shift of 2-3, Ly a photon in the galaxies in the escape ratio of fLy alpha csc14% (84% confidence). Our data exclude fLy alpha csc5.7%. on the confidence level of 99.87%
Then we transferred to the optical properties of Lehmann alpha galaxy. The sixth chapter to the eight, we identified 4.5 Lehmann spectral redshift observation alpha Galaxy sample based on Lehmann a luminosity function are discussed, the Lehmann alpha equivalent width distribution, as well as Lehmann alpha galaxy. In the sixth chapter is the analysis of the luminosity function, we the integrated luminosity function all at redshift 4.5 Lehmann a galaxies, and compare with the other at the redshift luminosity function. We found that the existence of Lehmann alpha Galaxy luminosity function evolution, and Lehmann alpha photon luminosity function integral Lehmann alpha Galaxy obtained by density over the entire stage with UV band cosmology selected star forming galaxies consistent means that the universe scale Lehmann alpha photon ratio is constant. In the seventh chapter, we use the equivalent width distribution, band ratio instead of direct calculation of equivalent width, the development of Monte Carlo Comparative analysis method relies on the equivalent width and line luminosity, it was found that the strength of equivalent width obeys the exponential distribution and does not depend on the line. The Monte Carlo method we contribute to the design of future narrow band survey. In the eighth chapter, we analyze the clustering of galaxies into spectra after identification, confirmed previously only based on group of selected samples. Conclusion a photometry we found Lehmann son of alpha photometric samples did not show a large group, which is different from the previous conclusion.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2012
【分类号】：P152

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