Radio variability properties for radio sources

Abstract

In this paper, we used the database of the university of Michigan Radio Astronomy Observatory (UMRAO) at three (4.8 GHz, 8.0 GHZ, and 14.5 GHz) radio frequency to analyze the radio light curves by the power spectral analysis method in search of possible periodicity. The analysis results showed that the radio sources display astrophysically meaningful periodicity ranging from 2.2 to 20.8 years in their light curves at the three frequencies. We also calculated the variability parameters and investigated the correlations between the variability parameter and the flux density. For the variability parameters, we found that the parameters at higher frequency are higher than those in the lower frequency. In addition, the variability parameters of BL Lacertae objects are larger than those of flat-spectrum radio quasars. suggesting that they are more variable than flat spectrum radio quasars.

Intra-day variability observations of S5 0716+714 over 4.5 years at 4.8 GHz

“…On the other hand, considering that the position angle of the 0716+714 jet is close to the anisotropy angle derived from our ISS model fit, it is plausible that the anisotropic scattering is caused by a sourceintrinsic anisotropy. Because the inner-jet position angle is oscillating from ∼10 • to ∼35 • following a 5.7 ± 0.5-year long-term variability cycle in the total flux density of 0716+714 (Raiteri et al 2003;Fan et al 2007;Britzen et al 2009), the anisotropy angle may vary accordingly. This would also contribute to an increase of the χ 2 r of the annual modulation fit.…”

Optical monitoring of BL Lac object S5 0716+714 and FSRQ 3C 273 from 2000 to 2014

“…There are many sources showing quasi-periods, such as 3C 273, 3C 279, 3C 454.3, Mrk335, Mrk 421, Mrk 501, OJ287, 0109+224, 0735+178, 2200+420, and so on (Kunkel 1967;Sillanpaa et al 1988;Chertoprud et al 1973;Stickel et al 1993;Fan et al 1998Fan et al , 2007Fan et al , 2014Fan & Lin 2000;Xie et al 2002;Raiteri et al 2001;Ciprini et al 2003). Explanation of the long-term variations could be based on the binary black-hole model, the thermal instability model or the perturbation model, and so on (Fan et al 2007).…”

“…Explanation of the long-term variations could be based on the binary black-hole model, the thermal instability model or the perturbation model, and so on (Fan et al 2007). …”

A kinematic study of the compact jet in quasar B3 1633+382

“…Binary black hole (BBH) models have been employed to explain similar component motions in other sources (e.g., 1803+784, Britzen et al 2010;Roland et al 2008;3C 345, Lobanov & Roland 2005). The component B3 1633+382 has been shown to exhibit periodicities in the radio (Fan et al 2007) and in the optical (Bozyan et al 1990) lightcurves, while also being variable in the γ-rays (Fan et al 2002). Quasi-periodic variability across the spectrum is a further argument in favor of a BBH in the nucleus of this object (Karouzos et al 2010;e.g., OJ 287, Sillanpaa et al 1988;Lehto & Valtonen 1996;3C 454.3, Qian et al 2007).…”