MOMO - V. Effelsberg, Swift, and Fermi study of the blazar and supermassive binary black hole candidate OJ 287 in a period of high activity

July 2022 • 2022MNRAS.513.3165K

Authors • Komossa, S. • Grupe, D. • Kraus, A. • Gonzalez, A. • Gallo, L. C. • Valtonen, M. J. • Laine, S. • Krichbaum, T. P. • Gurwell, M. A. • Gómez, J. L. • Ciprini, S. • Myserlis, I. • Bach, U.

Abstract • We report results from our ongoing project MOMO (Multiwavelength Observations and Modelling of OJ 287). In this latest publication of a sequence, we combine our Swift UVOT-XRT and Effelsberg radio data (2.6-44 GHz) between 2019 and 2022.04 with public SMA data and gamma-ray data from the Fermi satellite. The observational epoch covers OJ 287 in a high state of activity from radio to X-rays. The epoch also covers two major events predicted by the binary supermassive black hole (SMBH) model of OJ 287. Spectral and timing analyses clearly establish: a new UV-optical minimum state in 2021 December at an epoch where the secondary SMBH is predicted to cross the disc surrounding the primary SMBH; an overall low level of gamma-ray activity in comparison to pre-2017 epochs; the presence of a remarkable, long-lasting UV-optical flare event of intermediate amplitude in 2020-2021; a high level of activity in the radio band with multiple flares; and particularly a bright, ongoing radio flare peaking in 2021 November that may be associated with a gamma-ray flare, the strongest in 6 yr. Several explanations for the UV-optical minimum state are explored, including the possibility that a secondary SMBH launches a temporary jet, but the observations are best explained by variability associated with the main jet.

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Seppo Laine

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