Warm Absorbers In Active Galactic Nuclei

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.