@article{4d377e0a76de46779627cd60e5f7e896,
title = "OJ287: Deciphering the 'Rosetta stone of blazars",
abstract = "OJ287 is the best candidate active galactic nucleus (AGN) for hosting a supermassive binary black hole (SMBBH) at very close separation. We present 120 Very Long Baseline Array (VLBA) observations (at 15 GHz) covering the time between April 1995 and April 2017. We find that the OJ287 radio jet is precessing on a time-scale of ∼22 yr. In addition, our data are consistent with a jet-axis rotation on a yearly time-scale. We model the precession (24 ± 2 yr) and combined motion of jet precession and jet-axis rotation. The jet motion explains the variability of the total radio flux-density via viewing angle changes and Doppler beaming. Half of the jet-precession time-scale is of the order of the dominant optical periodicity time-scale. We suggest that the optical emission is synchrotron emission and related to the jet radiation. The jet dynamics and flux-density light curves can be understood in terms of geometrical effects. Disturbances of an accretion disc caused by a plunging BH do not seem necessary to explain the observed variability. Although the SMBBH model does not seem necessary to explain the observed variability, an SMBBH or Lense-Thirring precession (disc around single BH) seem to be required to explain the time-scale of the precessing motion. Besides jet rotation also nutation of the jet axis could explain the observed motion of the jet axis. We find a strikingly similar scaling for the time-scales for precession and nutation as indicated for SS433 with a factor of roughly 50 times longer in OJ287.",
keywords = "BL Lacertae objects: individual: OJ287, black hole physics, techniques: interferometric",
author = "S. Britzen and C. Fendt and G. Witzel and Qian, {S. J.} and Pashchenko, {I. N.} and O. Kurtanidze and M. Zajacek and G. Martinez and V. Karas and M. Aller and H. Aller and A. Eckart and K. Nilsson and P. Ar{\'e}valo and J. Cuadra and M. Subroweit and A. Witzel",
note = "Funding Information: The authors thank both anonymous referees for carefully reading the manuscript and for many helpful suggestions that significantly improved the paper. We are thankful to P. Falke, P. Biermann, S. Komossa, D. Champion, V. M. Pati{\~n}o-{\'A}lvarez, J. Roland, and N. Marchili for very helpful and insightful discussions. The help by K. Gab{\'a}nyi is greatly appreciated. O. Kurtanidze acknowledges financial support by the Shota Rustaveli National Science Foundation under contract FR/217554/16. Support for this work was provided by NSF grants AST-0909218 and AST-1412615 and the Levine-Leichtman Family Foundation. M. Zajacek is grateful for the financial support of the SFB956 {"}Conditions and Impact of Star-formation{"} (sub-project A2-{"}Conditions for Star Formation in Nearby AGN and QSO Hosts{"}) based at the Universities of Cologne and Bonn, and the MPIfR. This research has made use of data from the MOJAVE data base that is maintained by the MOJAVE team (Lister et al. 2009). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research was supported in part by NASA Fermi Guest Investigator awards NNX09AU16G, NNX10AP16G, NNX11AO13G, and NNX13AP18G, and by a series of grants from the NSF, most recently AST-0607523, which made the long-term UMRAO programme possible. Additional support for the operation of UMRAO was provided by the University of Michigan. Funding Information: The help by K. Gab?nyi is greatly appreciated. O. Kurtanidze acknowledges financial support by the Shota Rustaveli National Science Foundation under contract FR/217554/16. Support for this work was provided by NSF grants AST-0909218 and AST-1412615 and the Levine-Leichtman Family Foundation. M. Zajacek is grateful for the financial support of the SFB956 {"}Conditions and Impact of Star-formation{"} (sub-project A2- {"}Conditions for Star Formation in Nearby AGN and QSO Hosts{"}) based at the Universities of Cologne and Bonn, and the MPIfR. This research has made use of data from the MOJAVE data base that is maintained by the MOJAVE team (Lister et al. 2009). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This research was supported in part by NASA Fermi Guest Investigator awards NNX09AU16G, NNX10AP16G, NNX11AO13G, and NNX13AP18G, and by a series of grants from the NSF, most recently AST-0607523, which made the long-term UMRAO programme possible. Additional support for the operation of UMRAO was provided by the University of Michigan. Publisher Copyright: {\textcopyright} 2018 The Author(s).",
year = "2018",
doi = "10.1093/mnras/sty1026",
language = "English",
volume = "478",
pages = "3199--3219",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "3",
}