MOMO IV: The complete Swift X-ray and UV/optical light curve and characteristic variability of the blazar OJ 287 during the last two decades

Abstract

We are carrying out a dense monitoring of the blazar OJ 287 with Swift since late 2015 as part of our project MOMO (Multiwavelength Observations and Modeling of OJ 287). This is the densest existing monitoring of OJ 287 involving X-ray and UV data. In this latest publication of a sequence, we characterize the multiwavelength variability of OJ 287 based on >4000 Swift single-wave-band data sets including archival data since 2005. A structure function analysis reveals a characteristic timescale of ~5 days in the optical-UV at epochs of low-level activity, and larger during outbursts. The discrete correlation function shows zero lag between optical and UV, with tau = 0+-1 days at the epoch of densest cadence. During outbursts (in 2016/17 and 2020) the X-rays follow the UV with near-zero lags. However, during quiescence, the delay is 7-18 days with X-rays leading or lagging, interpreted as due to a different X-ray component dominated by inverse Compton emission. Scaling relations are used to derive the characteristic length scales of broad-line region and torus in OJ 287. A remarkable, symmetric UV--optical deep fade is identified in late 2017, lasting for 2 months. We rule out occultation from the passage of a dusty cloud and a model where the secondary black hole deflects the jet between the primary and observer. We speculate about a temporary dispersion or jet swing event in the core or in a bright quasi-stationary jet feature. The deep fade reveals an additional, spatially distinct X-ray component. The epoch 2020.9-2021.1 was searched for precursor flare activity predicted by the binary black hole model of OJ 287.

Results are part of a sequence of publications, previous and upcoming, from our ongoing project MOMO focussed on OJ 287. Accepted in July 2021, published December 9 in the Astrophysical Journal (ApJ 923, 51, 2021)

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Cited by in corpus (11)

• Absence of the predicted 2022 October outburst of OJ 287 and implications for binary SMBH scenarios
• Unravelling the Innermost Jet Structure of OJ 287 with the First GMVA+ALMA Observations
• MOMO VI: Multifrequency radio variability of the blazar OJ 287 from 2015-2022, absence of predicted 2021 precursor-flare activity, and a new binary interpretation of the 2016/2017 outburst
• Refining the 2022 OJ 287 impact flare arrival epoch
• X-ray timing and spectral variability properties of blazars S5 0716+714, OJ 287, Mrk 501, and RBS 2070
• MOMO V. Effelsberg, Swift and Fermi study of the blazar and supermassive binary black hole candidate OJ 287 in a period of high activity
• Host galaxy magnitude of OJ 287 from its colours at minimum light
• K2 Optical Emission from OJ 287 and Other Gamma-Ray Blazars on Hours-to-Weeks Timescales from 2014-2018
• Exploration of the origin of 2020 X-ray outburst in OJ 287
• Searching for supermassive black holes binaries within SRG/eROSITA-De I: Properties of the X-ray selected candidates
• Multiwavelength astrophysics of the blazar OJ 287 and the project MOMO