Long-term variation time scales in OJ 287

Abstract

The light curve data from 1894 to 2008 are compiled for the BL Lacertae object OJ 287 from the available literature. Periodicity analysis methods (the Discrete Correlation Function-DCF, the Jurkevich method, the power spectral (Fourier) analysis, and the CLEANest method) are performed to search for possible periodicites in the light curve of OJ 287. Significance levels are given for the possible periods. The analysis results confirm the existence of the 12.2 ± 0.6 yr time scale and show a hint of a ∼53 yr time scale. The 12.2±0.6 yr period is used as the orbital period to investigate the supermassive binary black hole system parameters.

Comparison of correlation analysis techniques for irregularly sampled time series

“…This technique was proposed by Mayo in 1978 and further elaborated by Edelson and Krolik (1988). It has become popular in velocimetry (Broersen et al, 2000) and is frequently applied in astronomy (Böttcher and Dermer, 2010;Fan et al, 2010;Nieppola et al, 2009;Zhang et al, 2010). The disadvantage of this technique is that, without post-processing, the correlation function estimates are not necessarily positive semidefinite and the spectra computed from their Fourier transform can show negative power.…”

Long-term optical and radio variability of BL Lacertae

“…P 2 ; P 4 ; P 6 ; P 8 and P 9 are likely to be two, three, four, five and six times of P 1 , respectively. The Jurkevich method (Jurkevich, 1971) is based on the expected mean square of deviation, and can probe periods without producing fake periods (Fan et al, 2010). Normalized V 2 m for light curves in B and V bands are shown in Fig.…”

“…4, and the minima of V 2 m indicate possible periods. To confirm the existence of periods, we adopted the False Alarm Probability (FAP) to provide a quantitative criterion (Horne and Baliunas, 1986;Fan et al, 2010). The horizontal dotted lines in Fig.…”

“…Raiteri et al (2001) recognized a $5.7 yr period in the radio light curves of AO 0235+16. A $12 yr period was detected in the optical flux variation of OJ 287 (Villata et al, 1998;Fan et al, 2010). Chen et al (2014) analyzed the optical light curves of Mrk 421 and found a possible period of 1.36 yr.…”

The analysis of radio and optical variability in blazar OQ 530

“…针对 Blazars 光变存在的周期性现象, 天文学家 提出了各种模型去解释(Fan 2005) [52] : 双黑洞模型, 螺旋喷流模型, slim 盘模型及吸积率的变化等. 其中 双黑洞模型合理解释了部分 Blazars 光变的周期, 如: OJ 287(Fan 等人) [8] 、PKS 1510-089(Wu 等人) [53] 、 Mkn 501(Rödig 等人) [54] 、3C 120 (Caproni 等人) [55] 和 3C 345(Caproni 等人) [56] . 我们认为 OQ 530 的光变可 能对应着螺旋喷流模型, 它认为 Blazars 的光变可能 是由于双黑洞绕转使得喷流的辐射取向发生了变化, 从而导致束流因子的变化, 而束流因子的变化又导 致了全电磁波段辐射流量的变化.…”