Study On The Spectral Energy Distribution And Light Variation Of Blazars

Active galactic nuclei(AGN)is one of the most popular study aspects in astrophysics,especially blazars should be attached importance to.Blazars are the most extreme AGN pointing the jets of AGN are equipped with relativistic and pointed to the jets in the direction of the observer.They have some features such as high luminosity,high polarization,apparent superluminal motion and rapid variability the typical broadband spectral energy distribution of a blazar displays a two component structure in the v loglog-vFv diagram.In this paper,we mainly explore the light variation of blazars and the physical properties of energy spectra.The first chapter mainly introduces the basic characteristics,classifications and standard models of active galactic nuclei.The second chapter and the third chapter mainly introduce the observation characteristics,energy spectrum distribution,leptons model,hadrons model,and light-variation of blazars.In the Chapter 4,we mainly analyze the light variation of the blazar PKS 1510-089.PKS 1510-089 is a variable,highly polarized FSRQs,whose red-shift is 0.36.It is one of the brightest and most variable blazars detected by Fermi LAT.Its most interesting feature is the cyclical outburst of the light variation and the periodic variation of the minimum flow rate.In order to further verify the authenticity of these cycles,and solve the problem of temporal discontinuities in observation data.In this paper,we have collected the data of V,J,R three bands which belong to the PKS1510-089,and used the method of the Date Compensated Discrete Fourier Transform(DCDFT)to analyze the light period and then compere with the method of Jurkevich.The method of DCDFT can deal with uneven astronomical observations effectively,and carry out Gram-Schmidt,which can solve the problem of false signals origins from non-orthogonality of the 1,cos?t,sin?t.The result show that the light period is T = 0.88 ? 0.08 yr in V,J,R three band by using DCDFT,which is consistent with the results of other who use different methods from ours(Fu et al).It shows that the DCDFT method is feasible in dealing with astronomical data.In the Chapter 5,we mainly study the energy spectrum characteristics of blazars.We collect 172 clean Fermi blazars with broadband quasi-simultaneous spectral data from radio to ?-ray.Both spectral energy distributions(SEDs)of synchrotron and inverse Compton(IC)components are fitted by a log-parabolic law in log?-log?F? diagram.The second-degree term of log-parabolic measures the curvature of SED.Our main intent is to explore the curvature properties of spectral energy distribution of Fermi blazars.Our main results are as follows: a significant correlation between the synchrotron peak frequency and its curvature for flat spectrum radio quasars(FSRQs)and BL Lacertae objects(BL Lacs)is found,but the correlation formulas are different for FSRQs and BL Lacs.Comparing with our observational results and the theoretical predictions of different models,we find that the observational results of FSRQs are consistent with the fluctuation of fractional acceleration gain model,while the observational results of BL Lacs are consistent with the energy-dependent acceleration probability model.The mean value of synchrotron curvature of FSRQs is larger than that of BL Lacs,which suggests the particle acceleration efficiency of BL Lacs is higher than that of FSRQs.It should be attributed to the jet plasma of FSRQs dissipated within the broad-line region(BLR)and suffered stronger cooling.We also find that FSRQs and Low-energy peaked BL Lacs(LBLs)have similar SED properties,which is consistent with previous results.But we don't find a significant correlation between the IC peak frequency and its curvature for FSRQs and BL Lacs,which may be caused by complicated seed photon field and radiation processes.