Core shift effect in blazars
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This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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en
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28
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Monthly Notices of the Royal Astronomical Society, Volume 469, issue 1, pp. 813-840
Abstract
We studied the pc-scale core shift effect using radio light curves for three blazars, S5 0716+ 714, 3C 279 and BL Lacertae, which were monitored at five frequencies (nu) between 4.8 and 36.8 GHz using the University of Michigan Radio Astronomical Observatory (UMRAO), the Crimean Astrophysical Observatory (CrAO) and Mets " ahovi Radio Observatory for over 40 yr. Flares were Gaussian fitted to derive time delays between observed frequencies for each flare (Delta t), peak amplitude (A) and their half width. Using A alpha nu(alpha), we infer a in the range of -16.67-2.41 and using Delta t alpha nu(1/kr), we infer k(r) similar to 1, employed in the context of equipartition between magnetic and kinetic energy density for parameter estimation. From the estimated core position offset (Omega(r nu)) and the core radius (r(core)), we infer that opacity model may not be valid in all cases. The mean magnetic field strengths at 1 pc (B-1) and at the core (B-core) are in agreement with previous estimates. We apply the magnetically arrested disc model to estimate black hole spins in the range of 0.15-0.9 for these blazars, indicating that the model is consistent with expected accretion mode in such sources. The power-law-shaped power spectral density has slopes -1.3 to -2.3 and is interpreted in terms of multiple shocks or magnetic instabilities.Description
Keywords
galaxies: active, quasars: individual: S5 0716+714, 3C 279, BL Lacertae, ACTIVE GALACTIC NUCLEI, EXTRAGALACTIC RADIO-SOURCES, BL LACERTAE OBJECTS, RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATIONS, MULTIBAND OPTICAL VARIABILITY, LIGHT-CURVE ANALYSIS, X-RAY VARIABILITY, BASE-LINE ARRAY, S5 0716+714, SUPERLUMINAL MOTION
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Citation
Agarwal, A, Mohan, P, Gupta, A C, Mangalam, A, Volvach, A E, Aller, M F, Aller, H D, Gu, M F, Lähteenmäki, A, Tornikoski, M & Volvach, L N 2017, 'Core shift effect in blazars', Monthly Notices of the Royal Astronomical Society, vol. 469, no. 1, pp. 813-840. https://doi.org/10.1093/mnras/stx847