摘要
在对活动星系核的X射线研究之中,温吸收占着很重要的一部分。它所描述的被电离的外流气体,在各个层面上限制着活动星系核的标准模型及其对周围环境的影响。随着观测手段的进步,温吸收展现了前所未有的丰富细节。本论文旨在研究温吸收在不同类型活动星系核中的异同,以及在X射线和紫外波段的相互关联,由此来揭示温吸收的本质。论文的具体结构如下:
第一章是对活动星系核的概述,介绍了标准模型的各个部分作为温吸收起源的可能性。主要包括了尘埃环热驱动所产生的热风,吸积盘的盘风,宽线区和窄线区的云块。同时为了证明活动星系核对周围环境的巨大影响,我们还简单提及了星系团的冷却流,MBH-σ关系和X射线背景。
第二章则重点论述温吸收的物理过程。介绍如何通过原子过程去使气体达到电离平衡与热平衡,以及随时间演化的非平衡电离的重要性。XSTAR软件是这章的另一主要内容,描述如何通过一些具体的物理参数来求得温吸收模型。
第三章总结了从第一次发现温吸收到高分辨率望远镜上天之前这段时间的研究成果。同时描述了高分辨率望远镜:Chandra与XMM-Newton的构造和观测能力。
第四章主要介绍Ⅰ型活动星系核中的温吸收。我们研究了Mrk 290这个典型Ⅰ型活动星系核的Chandra和XMM-Newton光谱数据,并从中发现了3个温吸收组分。这三个温吸收组分共同存在于尘埃环的热风区域,以每年约450kms-1的速度外流,并且在3年的时间里吸收柱密度有了缓慢的增加。这一章还描述了近十年中,一些经典源带来的有趣的结果,以及两个样本分析。
第五章主要介绍Ⅱ型与窄线Ⅰ型活动星系核中的温吸收。我们第一次描述了一个Ⅱ型活动星系核IRAS18325-5926中的温吸收特征。宽窄两个温吸收组分的柱密度在快速变化着,说明它们有很快的横向移动速度。我们建议这两个组分产生于之前高度电离盘的盘风,并且相互连接。这与Ⅰ型活动星系核中的吸积盘风模型相互吻合。窄线Ⅰ型活动星系核的特别的吸积过程,使得其中的温吸收气体也相对复杂。这里主要记录了十年来人们对NGC 4151和NGC 4051这两个源不休的争论与探讨,温吸收的激波模型也在这里被提出来。
第六章研究紫外吸收与温吸收的联系。首先概述了紫外吸收的观测历史与发展。然后介绍了一些紫外吸收与温吸收结合之后带来的新的视角。最后我们研究了Mrk 290的FUSE与HST/COS的光谱,确定了它的紫外吸收与X射线温吸收为同一气体产生。同时我们也探讨了宽线区和窄线区云块的电离水平和产生温吸收的能力。
第七章是对温吸收的简单总结和对将来工作的规划,以及对未来的X射线卫星的展望。
Warm absorber (WA) is a very important part in X-ray studies of active galactic nuclei (AGN). The ionized outflowing gas described by WA, constrains the AGN stan-dard model and the influence of AGN on surrounding environment in all aspects. With the progress of the means of observation, WAs show an unprecedented details. This pa-per aims to study the difference of WAs between different types of AGN, and between X-ray and ultraviolet band. Thus to reveal the nature of WAs. The paper is constructed as follows:
The first chapter is an overview of AGN, describing the various parts of the stan-dard model that could be the origin of WAs. That includes the thermal wind from the dusty torus, the wind from the accretion disk, the clouds in the broad line region or narrow line region. Moreover, to prove how tremendously the AGN can impact the sur-rounding environment, we also briefly mentioned the cooling flow of galaxy clusters, the MBH-σrelation, and the X-ray background.
The chapter two focuses on the physical process of WAs. We illuminate how the gas achieves the ionization equilibrium and the thermal balance through the atomic processes, and we also show the importance of the non-equilibrium ionization. XSTAR software is another major content of this chapter. We describe how to obtain a specific WA model with some physical parameters.
The chapter three summarizes the success of research from the time WA was found until the high resolution telescope was launched. It also describes the high resolution telescope:the structure and capacity of Chandra and XMM-Newton.
The WAs in type 1 AGN are discussed in the chapter four. The research of WAs in Mrk 290 is one of our works. This is a typical typeⅠAGN, we studied its Chandra and XMM-Newton spectral data, and identified three WA components. The three WAs co-exist in the thermal wind of the dusty torus, with an outflowing velocity at 450 km s-per year. Their column density increased slowly during the three years. This chapter also describes a number of classical sources which bring interesting results and two sample studies in the past decade.
The chapter five focuses on WAs of type 2 and narrow line type 1 AGNs. For the first time, we discuss the WAs in a type 2 AGN IRAS 18325-5926 with high resolution observation. The quick changing column density of the two WAs, suggests fast trans-verse velocity. The two WAs that could come from the highly ionized disk winds, may connect to each other. It can be explained with the disk wind model for type 1 AGNs. The WAs in narrow line type 1 AGNs are complicated due to the special accretion pro-cess. Here records how the people argued and debated for the WAs in NGC 4151 and NGC 4051. The shock model for WAs is mentioned here too.
The chapter six studies the connection between UV absorbers and X-ray WAs. We firstly overview the historical observations of UV absorbers, and then introduce some new perspective from UV absorbers. At last we studies the FUSE and HST/COS spectra of Mrk 290, to determine how the UV absorbers associate with WAs. We also discussed the ionization levels of broad and narrow line regions, and their capability to produce WAs.
The chapter seven is a brief summary of WAs' research, and the planning of future work. It shows the prospects for future X-ray satellite as well.
引文
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