Detection of a quasi-periodic oscillation in the optical light curve of the remarkable blazar AO 0235+164
Abhradeep Roy, V. R. Chitnis, Alok C. Gupta, Paul J. Wiita, Gustavo E. Romero, S. A. Cellone, A. Chatterjee, J. A. Combi, C. M. Raiteri, Arkadipta Sarkar, M. Villata
Abstract
ABSTRACT We present a long term optical R band light-curve analysis of the gravitationally lensed blazar AO 0235+164 in the time span 1982–2019. Several methods of analysis lead to the result that there is a periodicity of ∼8.13 yr present in these data. In addition, each of these five major flares are apparently double-peaked, with the secondary peak following the primary one by ∼2 yr. Along with the well-known system, OJ 287, our finding constitutes one of the most secure cases of long-term quasi-periodic optical behaviour in a blazar ever found. A binary supermassive black hole system appears to provide a good explanation for these results.