蝎虎天体OJ287中等时标光变的周期特性研究

A study of the middle time-scale periodic behavior of light curve of BL Lac object OJ287

收集了蝎虎天体OJ287光学B,V,R,I波段37年的观测数据,获得了从1972年至2009年的光变曲线.运用Lomb-Scargle傅里叶变换方法分析中等时标光变的周期性特性,发现存在52.0±1.1 d与255±23 d的主要周期成分,并模拟了存在倍周期分岔的准周期信号,与不同时段观测数据的相图和关联维数进行对比.结果表明,OJ287具有多周期尺度特征,不同时段准周期光变中谐波成分不同,谐波成分的变化与次黑洞对主黑洞吸积流的扰动有关,光变中的谐波成分可能是主黑洞吸积流受强扰动时分岔形成的.

In this paper, we collect the 37 years’ data observed for BL Lac object OJ287 in the optical band, and construct its light curve from 1972 to 2009. Using the method of Lomb-Scargle Fourier transform, we analyze the middle time-scale periodic behavior and discover the primary periodic compositions of 52.0 ± 1.1 day and 255 ± 23 day. Then, we simulate the quasi-periodic signal of period doubling bifurcations and compare it with the observation data at different time-interval in their phase diagram and correlation dimension. Result indicates that OJ287 has multi-period scale features. At different time-intervals, there are different harmonic period components in the quasi-periodic light curve. Variation of harmonic period component is related with the disturbance of accretion flow which is from the secondary black hole to the primary black hole, and the periodicity variability may bifurcate the harmonic period component when the primary accretion flow is influenced by a strong disturbance.