BL Lac天体OJ 287射电流量的交叉小波分析

将BL Lac天体OJ 287射电4.8,8.0和14.5 GHz波段从1978–2010年的有效观测数据进行整理,获得了其长期光变曲线,用小波功率谱和交叉小波方法分别分析了其主要振荡周期和彼此之间的相关性及其时延.小波功率谱分析结果表明,OJ 287射电4.8,8.0和14.5 GHz流量存在准6个月、8–16个月和16–32个月的主振荡周期,光变周期为0.54?0.04,1.12?0.07,2.49?0.08年,主振荡周期主要出现在1980–1994年和2000–2007年时间段.交叉小波分析发现OJ 287射电波段之间正相关振荡的凝聚性很强,具有强的关联性,在8–16和16–32个月共振周期尺度上的相关性高.射电波段的爆发在16–32个月的振荡周期尺度上几乎是同时性的,在8–16个月的振荡周期尺度上存在20±6天的时间延迟,高频波段领先低频波段.

Cross-wavelet analysis of the radio flux of BL Lac object OJ 287

We compile the radio light curve of BL Lac object OJ 287 at frequencies of 4.8, 8.0 and 14.5 GHz from 1978 to 2010. The continuous wavelet transform and the cross wavelet transform method are used to study the periodic oscillations of different significance, correlations, and time delays of OJ 287 in radio bands. The results of the continuous wavelet transform indicate that there are significant periods at scale of 6, 8-16 and 16-32 months （period of light variation, 0.54±0.04, 1.12±0.07, 2.49±0.08 year, and the significant wavelet spectrum of the radio flux is observed mainly from 1980 to 1994 and from 2000 to 2007. Based on the method of cross wavelet and wavelet coherence techniques, the coherence of positive correlation oscillations between the radio bands of OJ 287 is the highest, and the correlation degree is particularly strong, especially at oscillating period of 8-16 and 16-32 months. The outbursts of radio wavelengths are almost instantaneous at oscillating period of 16-32 months, and there is a minor time delay of 20±6 day at oscillating period of 8-16 months. High frequency band gets ahead of low frequency when they have a minor time delay.