Study On Multi-band Light Variability Analysis And Quasi-periodic Oscillation Of The Blazar

Active galactic nuclei(AGNs)are very energetic extragalactic sources powered by accretion on supermassive black holes.Blazars are the most extreme subclass of AGNs,with relativistic jets pointing in the direction of the observer,and they are characterized by rapid optical variation,high luminosity,high and variable polarization,apparent superluminal motion,non-thermal continuous radiation,and high-energy gamma-ray radiation.The exploration and research of blazars is of significance to the understanding of AGNs.Through the study of the optical variability of blazars,we can understand the complex physical phenomena and mechanisms inside.This article mainly analyzes and researches the optical data of different wavebands of blazars.The main content of this article is as follows.The first and second chapters introduce the related content of AGNs and blazars,and the third chapter mainly introduces the light variability of blazars.In Chapter 4,we used the 1.02 m optical telescope of Yunnan Observatory to obtain observation data of 8 typical blazars from 2010 to 2020,and processed the data using iraf software.We used the F test and ANOVA test methods to analyze the light variability of the blazars,and the results showed that the intraday variability was detected in 16 nights.The distributions of variability amplitudes most are from a few percent to 40%.We also analyzed the color index of these sources at different timescales.The results show that bluer-when-brighter(BWB)chromatic trend is dominant for our objects,while different timescales have different correlations.The shock in jet model gives a good explanation for this.In addition,we performed a periodic analysis of the intraday variability of 1ES1426+42.8.We found that 1ES 1426+42.8 may have a Quasi-periodic oscillation(QPO)(>3?)of P=48.67±13.90 minutes.The detection of the periodic variability on the intraday variability timescale can be most easily explained by the presence of a single dominating hot spot on the accretion disk or perhaps by pulsational modes in the disk.The minimum light variability timescales of the blazars were obtained through the autocorrelation function.Using these timescales and the quasi-periodic results,we estimated the mass of the black hole.The results are very close to the corresponding black hole mass in the relevant literature,which shows the reliability of the light variability timescales and period.In Chapter 5,we obtain the long-term timescale optical variability data of the blazar CGRa BS J0141-0928 in the 15 GHz radio band from the observation data of Owens Valley Radio Observatory 40 m telescope.We introduce Lomb scargle periodogram method,weight wavelet Z-transform method and Jurkevich method,respectively.These methods are used to analyze the light variable period of CGRa BS J0141-0928.The results show that the object has a QPO of about 649 days(4.4? significance level),and its QPO may be caused by the helical motion of the jet.The brightness temperature,timescale of light variability and Doppler factor were estimated by fitting the processes of two bursts with double exponential function.The Doppler factor estimated by the optical timescale of variability is 3.48,and the results show that CGRa BS J0141-0928 has a significant beaming effect in the radio radiation band.The discrete correlation function method is used to analyze the correlation between the radio band and gamma-ray and optical R band.It is found that there is a strong correlation between optical light variability and radio light variability,and the optical light variability is 66±40 days ahead of the radio variability.