Optical Variation Of Blazar Objects And Its Periodicity Analysis

Active galactic nuclei(AGNs), one of the most valuable research field in modern astrophysics. Blazar object is a class of the AGNs, the diference of optical variable for Blazar reflected its properties, structure and the different internal physical process. That will help us to know more about physical nature characteristics of AGNs, will get useful information about this kind of celestial body activity mechanism, and will be important implications for the AGNs model research.In this paper, Firstly, we introduce the relevant knowledge for AGNs; Secondly,introduction the optical variable of Blazar and The classification of the optical variable, the optical variable can be divided into short-term variability, when variability and long cycle variability, This paper mainly studies the objects of optical variable for a long cycle variability, and the variability period calculations of Blazar.thirdly, we introduce several methods of analyzing the Blazar variability period. At present, the methods are mainly include: Jurkevich method, wavelet analysis method,structure function method, power spectrum method, discrete correlation function analysis method. In the fourth chapter, briefly mentioning the analysis method which is applied to the signal analysis of Fourier transform, including continuous Fourier transform and discrete Fourier transform. The following describes another method of period analysis is Period04, one of the most commonly used analysis software in the astronomical community, especially the study of pulsating star. We mainly describe the interface, function, analysis steps of spectrum analysis software Period04.Finally, using the Period04 methods to study the the AGNs optical variability period. Collected long-term light observation datas of the quasar 3C 273 and BL Lac object OJ 287. Based on the observation datas, we analyze the period of light variation by using the Period04 software, and gain higher credibility period as a result:compared to other results, our period is basically identical. Then, a cycle inversion is carried out, and the observed data are fitted by using this period. It is basically consistent between the characteristic of the period fitting curve and the outbreakperiod of the observed data, which indicates that this period is more reliable. That period can be used to estimate the central black hole mass and the radius of the instability zones. The results showed that the Period04 method is reliable to analyze the period of Blazar.