Analyzing The Variations In The Spectral Energy Distribution Of The BL Lac Object Mrk 421

Mrk 421 is one of the closest Tev sources to Earth and the first observed extragalactic gamma-ray source of Tev energy.Since its discovery in 1992,Mrk 421 has been studied by scholars.According to the research approaches,it can be divided into two categories:the first approach is to study the light variation properties of the fixed band;the second approach is to collect the multi-band broadband energy spectrum data of Mrk 421,and then build a model for fitting,according to the fitting parameters of the model,the physical properties of the jet are studied.The second approach is adopted in this paper.In this paper,we collected the broadband spectral distribution data of 73 photovarying states of the flare Mrk 421 and fitted based on the single-region steadystate leptonian model,the electron energy distribution（EED）was first used as the turning power rate spectrum（BPL）to study the physical properties of Mrk 421 phototime-varying jets.,and the results are as follows:（1）There is a significant inverse correlation between magnetic field B and Doppler factor δ,indicating that B and δ are interdependent in the Thomson region;（2）The electron spectral indexp1supports the interpretation of shock wave or magnetic reconnection of Mrk 421 in light variation;（3）There is a positive correlation between the peak synchronization frequencylogvsynpk and the peak luminosity logv_syn^pk L_syn^pk,there is antiflare sequence in Mrk 421;（4）According to the equipartition parameter ε=U_e/U_B（Relativistic electron energy density U_e,magnetic field energy density U_B）,there are three cases of equipartition between U_e and U_B in Mrk 421 jet:Near equipartition（1<ε<10）、the electron energy is an order of magnitude greater than the magnetic field energy（10<ε<100）、the electron energy is much greater than the magnetic field energy（ε≥ 100）,the jet flow of Mrk 421 is dominated by particles.In this work,we found that EED was BPL could not fit all the states well,so we tried to analyze the physical properties of Mrk 421 jet by using EED as power rate+logarithmic parabolic spectrum（PLLP）.The results are as follows:（1）Mrk 421 there is no correlation between the inverse Compton component dominance CD and the synchronization peak-peak frequencyv_syn^pk when the light changes;（2）The magnetization parameterlogσ_m is negatively correlated with the IC peak-peak frequencylogv_IC^pk and the luminositylogvL_IC^pk,which indicates that the electron acceleration in the jet has an effect on the flare of y rays.The writing content of this article:the first chapter introduces the observation history,characteristics,classification and unified model of active galactic nuclei;chapter two describes subclass flare Distributions of active galactic nuclei according to its observation characteristics and Spectral Energy Distributions（SED）;chapter three introduces the two models of the bimodal structure in the flare SED pattern:the lepton model and the hadron model.The synchrotron radiation and inverse Compton scattering under the lepton model are introduced,and the hadron model is briefly introduced;chapter four introduces our specific work.