Jets And Accretion Of The Blazars

Active galactic nuclei(AGNs)are a class of objects with violent active phenomena,their activities are related to some physical processes:central black hole accretion,jets,relativistic high-energy particle production,and the interaction between black holes and the surrounding environment.Studying on AGNs is conducive to deepening the understanding of the evolution of the universe,galaxy formation and evolution,and central black hole formation and growth.Blazars are an extreme subclass of AGNs,can be divided into flat-spectrum radio quasars(FS-RQs),or BL Lacertae objects(BL Lacs).The jet direction is so close to the line of sight from observer that the radiations produced by blazars are enhanced by the beaming effect.Therefore,blazars have become an important research object to study the material accretion,jet generation and particle acceleration mechanism of extragalactic celestial bodies.This thesis takes the jets and accretion of the blazars as main research content,including the classifications,the relation between jets and accretion,the mechanism of jets formation,the mechanism of high-energy?-ray radiation,limitations and relationships of basic physical parameters.The content of this thesis is divided into three parts:the first part is the review part,the second part is arranged to introduce the research works containing five chapters,the third part is the outlooks on research works,details are as follows:Chapter 1,mainly introduces the obser-vational properties,classification and standard model of AGNs,the observational properties of the blazars including the jet effects and the spectral energy distributions(SEDs),the estimations of the central black hole mass and the central black hole spin?Secondly,the mechanism of ma-terial accretion,jet production,and the interconnection of accretion,spin,mass,and jet power are reviewed in detail?Finally,summarize the background and the significance for the research of our dissertation.Chapter 2,A large sample of radio sources is using to study the classification of radio loud(RL)and radio quiet(RQ)AGNs.From the 168,941 sources in the catalogue of quasars and active nuclei of the 13th edition,selecting 2419 radio sources as our sample with two data from radio bands and multiple data from optical bands,and applying a Gaussian mixture model from a Bayesian analysis to the distribution of radio loudness(log R)namely the ratio of radio flux to optical flux,then the dividing line between RL AGNs and RQ AGNs is log R=1.26?The machine learning algorithm is also used to classify RL AGNs and RQ AGNs with two parameters:radio luminosity and radio loudness,the results suggest that the classification of RL AGNs and RQ AGNs is not only related to radio loudness,but also to radio luminosity.Chapter 3,the connection between jets and accretion of RL Fermi blazars is studied and the method to estimate Doppler factor is proposed.Jet power and accretion luminosity are char-acterized by?-ray luminosity and BLR luminosity,respectively,and therefore the connection between jets and accretion can be explored from the correlation between?-ray luminosity and BLR luminosity.Based on?-ray data detected by Fermi Large Area Telescope(LAT)and the BLR data from the Sloan Digital Sky Survey(SDSS)database,through the matching for the coordinate of each object,50 Fermi blazars can be exploited and calculated with new BLR data,leading to 350 Fermi blazars in total with BLR luminosity.The strong correlation between?-ray luminosity and BLR luminosity is obtained,which supports that the intrinsic connection between jets and accretion.Meanwhile,in the view of the definition for the jet radiation power,the Doppler factor is calculated using the?-ray luminosity and the BLR luminosity.Chapter 4,the classification of the blazars is updated with the Fermi data,and the Blazars Candidate of Uncertain type(BCUs)in the sample is divided with this classification,the cor-relation of physical parameters such as black hole mass,accretion disk luminosity,jet power,and black hole spin of the blazars is studied.Then,?-ray luminosity,BLR luminosity,black hole mass,radio beam luminosity of 449 Fermi blazars were collected,the beam power and the black hole spin were calculated?The ratio of the BLR luminosity to the Eddington lumi-nosity is l BLR=log_LEdd^LBLR,then a Gaussian mixture model from Bayesian analysis was used to classify the distribution of l _BLR?The dividing line between FSRQs and BL Lacs was obtained with l _BLR=-3.14,this dividing line was used to divide BCUs and we obtained five changing look blazars,then we gave a list of candidates for the changing look blazars in this sample?The correlation studied among jet power,black hole mass,accretion disk luminosity and black hole spin,showed that the jets of blazars tend to be dominated by the Blandford-Znajek mechanism,in which the jet is extracted by the black hole rotation energy.Chapter 5,based on the one-zone lepton model,data on SEDs of 600 Fermi blazars is used to constrain the jet physical parameters,and we obtained the jet physical parameters such as the Doppler factor,the magnetic field strength,the region of the emission radiation,and the jet power.Our results showed that the location of emission region of FSRQs is close to the BLR region,and that of BL Lacs is between the BLR region and the dust torus region?The distribution of different forms of jet power(P_i)is related to its dominant mechanism,while the ratio(?_i=P_i/P_jet)to the jet power reflects the cooling efficiency.Chapter 6,we study the correlation between the multiband luminosities of Fermi blazars,explore which low-energy band radiation contributes the most to high-energy?-ray radiation,and analyze the origin mechanism of high-energy?-ray radiation?442 Fermi blazars were col-lected from the literature with radio luminosity,optical luminosity,X-ray luminosity,?-ray luminosity and redshift?Thus the Multiple Linear Regression was used to analyze the correla-tion between?-ray luminosity and luminosity of each other low-energy bands?The correlation between?-ray and radio luminosity is the strongest,while the one with optical luminosity is affected by the thermal radiation?The?-ray photons of HBLs are derived from SSC process,while that of FSRQs mainly come from EC process.Chapter 7 is the summary and outlook of my doctoral dissertation.