AO 0235+164射电波段宽带谱指数周期性变化的研究  

A Study of the Periodicity of Spectral Index in a Broad Radio Band of the BL Lac Object AO 0235+164

作　　者：梁继华[1] 张雄[1] 陈计贺 熊定荣[1] 刘文广[1] 

机构地区：[1]云南师范大学物理与电子信息学院,云南昆明650092 [2]宿州市时村中学,安徽宿州234109

出　　处：《天文研究与技术》2012年第2期107-113,共7页Astronomical Research & Technology

基　　金：国家自然科学基金(10763002)资助

摘　　要：收集了AO 0235+164天体射电4.8 GHz和14.5 GHz波段的光变测量数据,并获得了长期的光变曲线,从光变曲线可以看出其活动是非常剧烈的。利用Jurkevich方法和自相关函数方法分别对AO 0235+164射电波段宽带谱指数进行周期性分析,并对流量和谱指数进行相关性分析,研究结果表明:(1)AO 0235+164天体射电波段4.8 GHz～14.5 GHz对应的宽带谱指数,可能存在5.30年的光变周期,与Liu等人用功率谱法在射电波段发现其流量密度可能存在5.59±0.47年的光变周期基本吻合;(2)宽带谱指数与流量密度之间存在相关性。We have collected from many references flux-density data of the BL Lac object AO 0235＋164 in the radio bands near 4.8GHz and 14.5GHz within about 20 years. We construct long-term light curves for the object. The light curves show that the AO 0235＋164 is very active. We use the Jurkevich method and the Discrete Correlation Function （DCF） to analyze the period of the spectral index across the broad radio band 4.8GHz to 14.5GHz. The DCF was introduced by Edelson ＆ Krolik （1988）. The Jurkevich method and the DCF method are good in the sense that all data are used and there is no need to interpolate to set artificial datapoints. In addition, the DCF method also gives a reasonable error estimate. We also study possible correlations between flux density and the broad-band spectral index using the linear-regression method. Our results lead to the conclusions as follows. （i） The broad-band spectral index has a period of variation of about 5.30 years. Such a conclusion is consistent with the period of 5.59 ±0.47 years for the flux densities in radio bands found by previous studies （F. K. LIU. ）. The result also agrees with the near-equility of variation periods for optical flux densities and spectral indices found by Zheng et al. （2008）. （ii） There is a strong correlation between the broad-band spectral index and the flux density at 4. 8GHz, but there is an anti- correlation between the broad-band spectral index and the flux density at 14.5GHz. This is consistent with the analysis results of correlations between the broad-band spectral index and the flux densities at the 22GHz and 37GHz bands of the BL Lac object Mkn 421 （ Li et al. 2011 ）.

关 键 词：AO 0235+164 宽带谱指数 DCF和J—K方法 周期 相关性分析 

分 类 号：P157.7[天文地球—天文学]