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Location of γ-ray e...
Location of γ-ray emission and magnetic field strengths in OJ 287
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- Hodgson, J.A. (author)
- 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)
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- Krichbaum, T.P. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Marscher, A.P. (author)
- Boston University
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- Jorstad, S.G. (author)
- Saint Petersburg State University - Spsu,Boston University
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- Rani, B. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Marti-Vidal, Ivan, 1980 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Bach, U. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Sanchez, S. (author)
- Institut de Radioastronomie Millimétrique (IRAM)
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- Bremer, M. (author)
- Institut de Radioastronomie Millimétrique (IRAM)
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- Lindqvist, Michael, 1960 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Uunila, M. (author)
- Aalto-Yliopisto,Aalto University
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- Kallunki, J. (author)
- Aalto-Yliopisto,Aalto University
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- Vicente, P. (author)
- Observatorio de Yebes (IGN),Yebes Observatory
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- Fuhrmann, L. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Angelakis, E. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Karamanavis, V. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Myserlis, I. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Nestoras, I. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Chidiac, C. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Sievers, A. (author)
- Institut de Radioastronomie Millimétrique (IRAM)
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- Gurwell, M. (author)
- Harvard-Smithsonian Center for Astrophysics
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- Zensus, A.J. (author)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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Korea Astronomy and Space Science Institute Max Planck Gesellschaft zur Förderung der Wissenschaften eV. (MPG) (creator_code:org_t)
- 2017-01-06
- 2017
- English.
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 597, s. 80-
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Abstract
Subject headings
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- 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
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Keyword
- Techniques: high angular resolution
- Techniques: interferometric
- Galaxies: active
- BL Lacertae objects: individual: OJ 287
- Galaxies: jets
- Magnetic fields
Publication and Content Type
- art (subject category)
- ref (subject category)
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To the university's database
- By the author/editor
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Hodgson, J.A.
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Krichbaum, T.P.
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Marscher, A.P.
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Jorstad, S.G.
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Rani, B.
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Marti-Vidal, Iva ...
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show more...
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Bach, U.
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Sanchez, S.
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Bremer, M.
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Lindqvist, Micha ...
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Uunila, M.
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Kallunki, J.
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Vicente, P.
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Fuhrmann, L.
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Angelakis, E.
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Karamanavis, V.
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Myserlis, I.
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Nestoras, I.
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Chidiac, C.
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Sievers, A.
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Gurwell, M.
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Zensus, A.J.
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show less...
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- NATURAL SCIENCES
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NATURAL SCIENCES
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Astronomy and As ...
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Chalmers University of Technology