Study On Accretion Disk And Color Index Of Blazars

Active galaxy nuclei(AGNs)have become a hot topic in the field of contemporary astrophysics due to their particularity.Blazars are the most active subclass in active galaxy nuclei,with observation phenomena and physical characteristics such as high luminosity,high polarization,and rapid and large optical variability,which reflect their structure and physical processes.So that they can better study the evolutionary sequence,radiation mechanism and structural model of the Blazars.Blazars can be divided into two categories:flat-spectrum radio quasars(FSRQs)have strong emission lines,and the rest frame equivalent width(EW)of their broad emission lines is greater than 5?;the BL Lacs have no or weaker emission line.This paper mainly researches the accretion disk scales of radiation parameters and the correlation between flux and color index of the Blazars.This article is divided into five chapters.The first chapter is a brief introduction to the Blazars,which mainly introduces the observational characteristics,classification,models of AGNs,and observational characteristics of Blazars.The second chapter is the radiation characteristics and radiation mechanism of the Blazars.It mainly introduces the radiation characteristics of the optical and high-energy bands and the five types radiation mechanisms of Blazars.The third chapter is the optical variability of Blazars.It mainly introduces three types of optical variability time scales,photometric observations and optical variability models.Chapter 4 analyzes the radius of the radiation area of AGN accretion disk by standard accretion disk method,short time optical variation method,continuum reverberation lag method and gravitational microlensing method.The results show that:(1)there is no significant difference in the _u,the luminosity or the radius of the radiation area of the accretion disk between the blazars and the quasars.This paper selects the high luminosity source for research,so there is no obvious difference above parameters of the subcategory;(2)The radius ratio of the radiation area of AGN accretion disk obtained by the short time optical variability has not a dependence on the _u;(3)The radius ratio of radiation area of AGN accretion disk obtained by the continuous reverberation lag method is more dependent on the black hole than the standard?disk model method.For the source that cannot determine the _u,the radius of radiation area of AGN accretion disk can be obtained by the continuous reverberation lag method;(4)There is no obvious correlation between the radius of radiation area of AGN accretion disk by the gravitational microlensing method and the _u,and the method is only applicable to quasars with micro-gravitational lens effects;(5)These methods prove that the radius of the radiation area of AGN accretion disk is directly proportional to the mass of the black hole,which verifies that the standard model is established.Provides theoretical guidance for further exploration of the sources needed for these four methods.It is important to study the radius of the radiation area of AGN accretion disk.In Chapter 5,the optical band flux and color index of 19 Fermi Blazars are corrected by modulating the flux base-level.By comparing the correlation between the color index and the magnitude before and after the correction,the effect of the Doppler factor on the color index change mechanism is studied.Studies show that:(1)only five sources showed a clear BWB trend before the correction,and two sources showed a clear RWB trend;(2)after the correction,nine sources showed a clear BWB trend,and six sources showed a weak BWB trend,only the color indices of 4 sources have no correlation with the magnitude;(3)The color change mechanism of about half of the sources is affected by the Doppler beamforming effect.After correction,the correlation between the color index and magnitude of these sources is enhanced;(4)The change of the Doppler factor may be the cause of the weakening of the BWB trend.By studying the correlation between the color index and the magnitude,the radiation mechanism of Blazars can be further explained.