The Light Of Active Galactic Nuclei Change And Evolution

In this thesis, we review the basic properties, classification, variability, black hole, theory model and evolution of the active galactic nuclei (AGNs). We have analyzed the periodicity of light curve of some sources, estimated the black hole masses of some source and investigated the evolution of AGN.Our main works and results are as follow: (1) the periodicity analysis of the light curve of 3C 454. 3. We present an analysis of the radio light curve of the source 3C 454. 3 at frequency 22 and 37 GHz by using the Jurkevich and the power spectrum density estimating methods, basing on the database of Metahovi Radio Observatory. We found that it exhibits two possible period: 6.15 years and 1. 57 years. For the periodicity of 6. 15 years, we apply the binary black hole model to explain the central structure of this object. Through a simple estimation, we obtain the masses of primary and secondary black hole which are l.53×10⁹M(?) and 1.86×10⁷M(?), respectively. The distance between the two black holes is 5.88×10¹⁶cm and their life time is 2.37×10⁵ years. In addition, the luminosity of gravitational wave emitted is 3.28×10⁴⁶ergss^-1. For the periodicity of 1. 57 years, we consider it is caused by helical jet, namely, the emission variability is due to the viewing angle change. (2) The periodicity analysis of the light curve of Seyfert galaxies of III Zw 002. We present an analysis of the radio light curve of the source 3C 454. 3 at frequency 22 and 37 GHz by using the Jurkevich, the power spectrum density estimating and the discrete correlation function methods, basing on the database of Metahovi Radio Observatory. We found that it exhibits periodic outbursts at intervals 5. 15 years witch is consistent with the...