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Galaxies 2017, 5(1), 12; doi:10.3390/galaxies5010012

OJ 287 as a Rotating Helix

Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA
Academic Editors: Jose L. Gómez, Alan P. Marscher and Svetlana G. Jorstad
Received: 6 September 2016 / Revised: 9 January 2017 / Accepted: 16 January 2017 / Published: 8 February 2017
(This article belongs to the Special Issue Blazars through Sharp Multi-wavelength Eyes)
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Abstract

We present preliminary data from high-cadence 15-GHz VLBA images of OJ 287 from 1995 to 2015. The ridgelines suggest that the jet is rotating, perhaps with a period of∼30 years. The EVPA of the core rotated by 240° in 2001–2002 and decreased slowly after that. The inner jet apparently moved to a new direction after the rotation,as shown by the emergence of a new component at a new PA at 43 GHz, in 2004. This was presaged by a strong rise in the flux density of the core, and then its sudden fall as the new component was identified. The equivalent sequence of events took place about 5 years later at 15 GHz, but in addition the core EVPA had a step in 2006 and moved to be aligned with the new 43-GHz component. The 15-GHz core became optically thin in 2006, but the angular resolution was insufficient to separate the new component from the core until 2010 View Full-Text
Keywords: BL Lacertae objects: individual (OJ 287); galaxies: active; galaxies: jets; magnetohydrodynamics (MHD); waves BL Lacertae objects: individual (OJ 287); galaxies: active; galaxies: jets; magnetohydrodynamics (MHD); waves
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Cohen, M.H. OJ 287 as a Rotating Helix. Galaxies 2017, 5, 12.

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