The Study Of Blazar's Beaming Effect In AGNs

The active galactic nucleus (AGNs) is one of the frontier fields of astrophysics research because of its unique observational characteristics. They have high luminosity, vriability, high and variable polarizations,strong emission line or weak even no emission lines,strong gamma-ray emission and superluminal motion. In order to explain these observational properties, a "black hole + jet +accretion disk" model was proposed. The subclasses may be due to differences in the viewing angle.The most extremely subclass is blazar. Its extreme observational properties may be caused by beaming effect. This master's thesis will discuss the beaming effect from several aspects. This paper is mainly composed of two parts. The first part mainly introduces the characteristics and classification of AGNs and beaming effect. The second part introduces the content of this paper.The first part includes chapters I and II:In the first chapter, the basic situation of the research on AGNs is introduced, including the basic characteristics of AGN and the classification which is based on the observations. In order to meet the observation, the "black hole - accretion disk" standard model and unified model are proposed. The second chapter mainly introduces the energy spectrum distribution (SED) of blazar,relativistic jet and beaming effect.The second part includes chapters III and IV; the content of this part can be divided into three parts:(1) Investigated the relations between the observed gamma-ray band flus density and the intrinsic flux density versus redshift. In addition, the observed gamma-ray luminosity and short-time relation do not satisfy the E-S and A-N relations. But after removed the beaming effect,the luminosity and short time scales satisfy the E-S and A-N relations, indicating that gamma-ray emission has a strong beaming effect. In order to study the beaming effect of blazars, 79 Fermi detected sources (FDS)were collected from the literature, including the corresponding Doppler factors and 36 sources with short-timescale variability in gamma-ray band. Use this sample to study the flux and luminosity of the Fermi blazers in gamma-ray band. The theory shows that the relationship between flus and redshift should satisfy the Hubble relation (logf= =21og z +const.), and the luminosity calculated from the flux should lower than the Eddington luminosity (LEdd). While the results show that the observed flux (fob) and the redshift relation (z) do not satisfy the Hubble relation, besides, a super-Eddington luminosity in gamma-ray luminosity. And this is the result of beaming effect. After removed the influence of the beaming effect, the flux-redshift relation satisfies the Hubble relation and the gamma-ray luminosity returns below Eddington's luminosity. These indicate that the Gamma emissions of blazar are beamed.(2) A sample of the superluminal sources was collected. Based on this sample,we compared the sources with gamma-ray emission (FDS) and the sources without gamma-ray emission (non-FDS),and found that the FDS show stronger beaming effect, and the superluminal sources tend to have high gamma-ray emission. This paper collected 274 superluminal motion sources including FDS and non-FDS. By comparing FDS and non-FDS's proper motion (?) and apparent velocity (?app),the results show that FDS has greater ?and ?app . But FDS also shows a larger Doppler factor and smaller viewing angle, which indicates that FDS has a stronger beaming effect than non-FDS, and the superluminal motion of AGNs can be used as an important probe of beaming effect. There is a tendency that sources with higher ganma-ray luminosity show a greater ?app ,and means a stronger beaming effect.(3) We study the relation between the Doppler factor and the brightness temperature using the brightness temperature and the apparent velocity obtained from literature. In this paper, we use the samples from three literatures to study the brightness temperature of AGN,and then explore the Doppler factor. In this paper, we assume that the observed bright temperature (Tob) and the intrinsic brightness temperature (Tin) are connected with ?x, where x is the Doppler factor index:Tob=?xT·in.The equilibrium brightness temperature given by the theory, Tin?Teq=5×1010K .x is the Doppler factor index,which can be determined by fitting according to the observed brightness temperature(Tob) and ?app.(?)Three values were set at 1.5, 2.5, and 2.4 for the three samples, respectively. The main conclusion of this section is that the x-factor of the sample can be set to make a accurate calculation for Doppler factor.Chapter 5 summarizes the full text and future research work prospects.