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  • Hodgson, J.A.Korea Astronomy and Space Science Institute,Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)

Location of γ-ray emission and magnetic field strengths in OJ 287

  • Article/chapterEnglish2017

Publisher, publication year, extent ...

  • 2017-01-06
  • EDP Sciences,2017
  • electronicrdacarrier

Numbers

  • LIBRIS-ID:oai:research.chalmers.se:d484c8db-497a-46ea-ab83-7bba07434e58
  • https://research.chalmers.se/publication/247696URI
  • https://doi.org/10.1051/0004-6361/201526727DOI

Supplementary language notes

  • Language:English
  • Summary in:English

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  • Subject category:art swepub-publicationtype
  • Subject category:ref swepub-contenttype

Notes

  • Context. The γ-ray BL Lac object OJ 287 is known to exhibit inner-parsec "jet-wobbling", high degrees of variability at all wavelengths and quasi-stationary features, including an apparent (≈100°) position-angle change in projection on the sky plane. Aims. Sub-50 micro-arcsecond resolution 86 GHz observations with the global mm-VLBI array (GMVA) supplement ongoing multifrequency VLBI blazar monitoring at lower frequencies. Using these maps, together with cm/mm total intensity and γ-ray observations from Fermi-LAT from 2008..2014, we aim to determine the location of γ-ray emission and to explain the inner-mas structural changes. Methods. Observations with the GMVA oer approximately double the angular resolution compared with 43 GHz VLBA observations and enable us to observe above the synchrotron self-absorption peak frequency. Fermi-LAT γ-ray data were reduced and analysed. The jet was spectrally decomposed at multiple locations along the jet. From this, we could derive estimates of the magnetic field using equipartition and synchrotron self-absorption arguments. How the field decreases down the jet provided an estimate of the distance to the jet apex and an estimate of the magnetic field strength at the jet apex and in the broad line region. Combined with accurate kinematics, we attempt to locate the site of γ-ray activity, radio flares, and spectral changes. Results. Strong γ-ray flares appeared to originate from either the so-called core region, a downstream stationary feature, or both, with γ-ray activity significantly correlated with radio flaring in the downstream quasi-stationary feature. Magnetic field estimates were determined at multiple locations along the jet, with the magnetic field found to be ≥1.6G in the core and ≤0.4G in the downstream quasi-stationary feature.We therefore found upper limits on the location of the VLBI core as ≤6.0 pc from the jet apex and determined an upper limit on the magnetic field near the jet base of the order of thousands of Gauss.

Subject headings and genre

Added entries (persons, corporate bodies, meetings, titles ...)

  • Krichbaum, T.P.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)
  • Marscher, A.P.Boston University (author)
  • Jorstad, S.G.Saint Petersburg State University - Spsu,Boston University (author)
  • Rani, B.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)
  • Marti-Vidal, Ivan,1980Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)mivan (author)
  • Bach, U.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)
  • Sanchez, S.Institut de Radioastronomie Millimétrique (IRAM) (author)
  • Bremer, M.Institut de Radioastronomie Millimétrique (IRAM) (author)
  • Lindqvist, Michael,1960Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)mlq (author)
  • Uunila, M.Aalto-Yliopisto,Aalto University (author)
  • Kallunki, J.Aalto-Yliopisto,Aalto University (author)
  • Vicente, P.Observatorio de Yebes (IGN),Yebes Observatory (author)
  • Fuhrmann, L.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)
  • Angelakis, E.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)
  • Karamanavis, V.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)
  • Myserlis, I.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)
  • Nestoras, I.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)
  • Chidiac, C.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)
  • Sievers, A.Institut de Radioastronomie Millimétrique (IRAM) (author)
  • Gurwell, M.Harvard-Smithsonian Center for Astrophysics (author)
  • Zensus, A.J.Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG) (author)
  • Korea Astronomy and Space Science InstituteMax Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG) (creator_code:org_t)

Related titles

  • In:Astronomy and Astrophysics: EDP Sciences597, s. 80-0004-63611432-0746

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