The Optical Variability of the BL Lac AO 0235+164

Junhui Fan,Chao Lin,Yi Liu,Maria Nikolashvili,Revaz Chanishvili,Omar Kurtanidze,Mahito Sasada,Xiang Liu,Aiying Zhou,Sophia Kurtanidze,Gotthard Richter,Hongtao Wang,Yuhai Yuan

doi:10.3390/galaxies4030017

Abstract

In this work, we present optical R band observations of AO 0235+164 carried out during the period of November 2006 to December 2012 using the Ap6E CCD camera attached to the primary focus of the 70 cm meniscus telescope at Abastumani Observatory, Georgia. It shows a large variation of Δ R = 4.88 mag (14.19–19.07 mag) and a short time scale of Δ T v = 73.5 min during our monitoring period. When periodicity analysis methods are applied to the R-band data from both historic and our observations, periods P 1 = 8.26 yr and P 2 = 0.54 yr are found.

Highlights

Blazars are a special subclass of Active Galactic Nuclei (AGN) showing extreme observed properties such as high luminosity, strong and variable gamma ray emission, strong or no emission features, high and variable polarization, and superluminal motion
The variations have been found to be over time scales from less than one hour to as long as years; see [5], who divided the time scales into three classes: micro-variability with time scale ∆T being less than one day; short-term variation (STV), with ∆T being one day to several months; and long-term variation (LTV), with
In the case that data are unevenly sampled in time series, the Jurkevich (JV) method [6] and improved power spectral analysis (PSA) will be adopted for the possible periodicities

Summary

Introduction

Blazars are a special subclass of Active Galactic Nuclei (AGN) showing extreme observed properties such as high luminosity, strong and variable gamma ray emission, strong or no emission features, high and variable polarization, and superluminal motion. A period of 5.87 ± 1.3 years was found in our pervious work based on 16 years of optical observations [9], but 5.8 ± 0.3 years (based on 14.5 GHz light curve), 5.7 ± 0.3 years (based on 8.0 GHz light curve), and 10.0 ± 1.3 years (based on 4.8 GHz light curve) are found in its radio bands [13]. This perhaps suggests the existence of a binary black hole system at its center [28,29].

Observations

Discussions and Conclusions

Summary