Study On The Properties Of The Spectral Energy Distribution Of Fermi Blazar Jet

Active galactic nuclei(AGN)is one of the most popular field of the study in astrophysics.Blazars are the most extreme AGN pointing their relativistic jets in the direction of the observer.Blazars have many extreme properties of AGN,such as high luminosity,high and variable polarization,broad band radiation,rapid variability.Generally,blazars are divided into flat spectrum radio quasars(FSRQs)and BL Lac objects(BL Lacs).Observationally,the typical broadband spectral energy distribution of a blazar displays a two-component structure in the log?-log? diagram.In the lepton model,low energy peak is generally accepted to derive from the synchrotron emission of relativistic electrons in the jet,and high energy peak is derived from inverse Compton(IC)scattering.The multi-waveband radiation of blazar is dominated by jet.By collecting the multi-waveband simultaneous observation data and fitting the SEDs,the properties of jet can be well researched.The first chapter of this thesis introduces the main observed characteristics of the AGN and blazar.The second chapter introduces the main properties of the broadband spectral energy distribution of blazar.The third chapter introduces the leptonic and hadronic jet models.My own research works are presented in chapter 4-6,all the three works are based on a large sample of Fermi 2LAC,and the simultaneous multi-waveband SEDs are fitted by the log-parabolic law.In the fourth chapter,we give the integral function of bolometric luminosity and use it to calculate the integrated bolometric luminosity of our sample.Then we take the integrated bolometric luminosity as benchmarking to evaluate and calibrate other six estimation methods.In the fifth chapter,we study the statistical properties of the curvature of the SEDs.Our main results are as follows.(1)We find a statistically significant correlation between the synchrotron peak frequency and its curvature.This correlation can be explained by the statistical and stochastical particle acceleration mechanisms.By analyzing our sample,we find that the particle acceleration mechanism between FSRQs and BL Lacs is different.In terms of the particle acceleration mechanisms,this is the first time that a difference between FSRQs and BL Lacs has been found using a large sample.(2)For FSRQs,we find no correlations between the synchrotron curvature and various basic parameters of blazars(broad-line luminosity,black hole mass,the Lorentz factor of the jet and the bolometric luminosity).However,the significant correlations between these four basic parameters and the IC curvature are found.We suggest that there might be a deep-seated physical significance.In the sixth chapter,we study whether the high energy radiation of FSRQs and BL Lacs is dominated by external Compton(EC)process or synchrotron-self Compton(SSC)process.Our main results are as follows.(1)For FSRQs,the high energy radiation is dominated by the EC process.While,for BL Lacs,it is dominated by the SSC process.(2)For the relative high synchrotron peak frequency FSRQs,its high energy radiation is more dominated by the SSC process.However,the study in the sixth chapter is not finished.In order to support the above statistical results,we need to build a reasonable jet model.