• Hao-Jing Zhang

      Articles written in Journal of Astrophysics and Astronomy

    • Long Term Periodicity Analysis of OJ 287 at Optical V Waveband

      Jie Tang Hao-Jing Zhang Qiao Pang

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      BL Lacertae object OJ 287 is one of the blazar that shows convincing evidence to support periodic variations. We have collected V band data for OJ 287 from 1891 to 2010, from the University of Michigan Radio Observatory (UMRAO) database and the available literature. Based on the spectral estimate theory, this paper used the periodogram spectral estimate, the maximum entropy spectral estimate and bispectrum spectral estimate methods. Applying these methods to the periodic analysis of OJ 287, we find the most eminent period as 12.1 yr. The results confirm that the variability period of OJ 287 in the optical V band is in agreement with the radio variability period of about 12 years.

    • Broad-Band Spectral Indices Variability of BL Lacertae by Wavelet Method

      Hao-Jing Zhang Jing-Ming Bai Yu-Ying Bao Xiong Zhang

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      BL Lacertae is one of the famous AGN that shows convincing evidence to support periodic variability. We compile R-band data and radio 22 GHz database from the available literature to build the light curves and to calculate broad-band spectral indices. This paper employs the wavelet periodic estimation method. The analysis results indicate that the most possible period is 7.02–7.36 yr in the selected wave-bands. The broad-band spectral indices have a possible period of 4.11 yr as a half value in selected wave-bands. The results confirm that the variability period in the radio 22 GHz is in agreement with the optical R band of about 7.01 yr, as also mentioned in other literatures.

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    • Continuous Article Publication

      Posted on January 27, 2016

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