Stochastic modeling of multiwavelength variability of the classical BL Lac Object OJ287 on timescales ranging from decades to hours
Goyal, A.; Stawarz, L.; Zola, S.; Marchenko, V.; Soida, M.; Nilsson, K.; Ciprini, S.; Baran, A.; Ostrowski, M.; Wiita, P. J.; Gopal-Krishna; Siemiginowska, A.; Sobolewska, M.; Jorstad, Svetlana; Marscher, Alan P.; 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.; Campas Torrent, M.; Campos, F.; Carrillo Gomez, J.; Dalessio, J.; Debski, B.; Dimitrov, D.; Drozdz, M.; Er, H.; Erdem, A.; Escartin Perez, A.; Ramazani, V. Fallah; Filippenko, A. V.; Gafton, E.; Garcia, F.; Godunova, V.; Gomez Pinilla, F.; 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.; Koziel-Wierzbowska, D.; Kuligowska, E.; Kundera, T.; Kurowski, S.; Kvammen, A.; LaCluyze, A. P.; Lee, B. C.; Liakos, A.; Lozano de Haro, J.; Moore, J. P.; Mugrauer, M.; Naves Nogues, R.; 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.; Salto Gonzalez, J. L.; Sameer; Simon, A. O.; Siwak, M.; Schweyer, T.; Soldan Alfaro, F. C.; Sonbas, E.; Strobl, J.; Takalo, L. O.; Tremosa Espasa, L.; 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.
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.
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