Stochastic Modeling of Multiwavelength Variability of the Classical BL Lac Object OJ 287 on Timescales Ranging from Decades to Hours
Authors: Goyal A. , Stawarz Ł. , Zola S. , Marchenko V. , Soida M. , Nilsson K. , Ciprini S. , Baran A. , Ostrowski M. , Wiita P. J. , Gopal-Krishna  , Siemiginowska A. , Sobolewska M. , Jorstad S. , Marscher A. , Aller M. F. , Aller H. D. , Hovatta T. , Caton D. B. , Reichart D. , Matsumoto K. , Sadakane K. , Gazeas K. , Kidger M. , Piirola V. , Jermak H. , Alicavus F. , Baliyan K. S. , Baransky A. , Berdyugin A. , Blay P. , Boumis P. , Boyd D. , Bufan Y. , Torrent M. Campas , Campos F. , Gómez J. Carrillo , Dalessio J. , Debski B. , Dimitrov D. , Drozdz M. , Er H. , Erdem A. , Pérez A. Escartin , Ramazani V. Fallah , Filippenko A. V. , Gafton E. , Garcia F. , Godunova V. , Pinilla F. Gómez , Gopinathan M. , Haislip J. B. , Haque S. , Harmanen J. , Hudec R. , Hurst G. , Ivarsen K. M. , Joshi A. , Kagitani M. , Karaman N. , Karjalainen R. , Kaur N. , Kozieł-Wierzbowska D. , Kuligowska E. , Kundera T. , Kurowski S. , Kvammen A. , LaCluyze A. P. , Lee B. C. , Liakos A. , Haro J. Lozano de , Moore J. P. , Mugrauer M. , Nogues R. Naves , Neely A. W. , Ogloza W. , Okano S. , Pajdosz U. , Pandey J. C. , Perri M. , Poyner G. , Provencal J. , Pursimo T. , Raj A. , Rajkumar B. , Reinthal R. , Reynolds T. , Saario J. , Sadegi S. , Sakanoi T. , González J. L. Salto , Sameer  , Simon A. O. , Siwak M. , Schweyer T. , Alfaro F. C. Soldán , Sonbas E. , Strobl J. , Takalo L. O. , Espasa L. Tremosa , Valdes J. R. , Vasylenko V. V. , Verrecchia F. , Webb J. R. , Yoneda M. , Zejmo M. , Zheng W. , Zielinski P. , Janik J. , Chavushyan V. , Mohammed I. , Cheung C. C. , Giroletti M. 
Published: August 2018

Abstract
We present the results of our power spectral density analysis for the BL Lac object OJ 287, utilizing the Fermi-LAT survey at high-energy γ-rays, Swift-XRT in X-rays, several ground-based telescopes and the Kepler satellite in the optical, and radio telescopes at GHz frequencies. The light curves are modeled in terms of continuous-time autoregressive moving average (CARMA) processes. Owing to the inclusion of the Kepler data, we were able to construct for the first time the optical variability power spectrum of a blazar without any gaps across ∼6 dex in temporal frequencies. Our analysis reveals that the radio power spectra are of a colored-noise type on timescales ranging from tens of years down to months, with no evidence for breaks or other spectral features. The overall optical power spectrum is also consistent with a colored noise on the variability timescales ranging from 117 years down to hours, with no hints of any quasi-periodic oscillations. The X-ray power spectrum resembles the radio and optical power spectra on the analogous timescales ranging from tens of years down to months. Finally, the γ-ray power spectrum is noticeably different from the radio, optical, and X-ray power spectra of the source: we have detected a characteristic relaxation timescale in the Fermi-LAT data, corresponding to ∼150 days, such that on timescales longer than this, the power spectrum is consistent with uncorrelated (white) noise, while on shorter variability timescales there is correlated (colored) noise.