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Title: Multiwavelength intraday variability of the BL Lacertae S5 0716+714
Authors: Gupta, A. C
Krichbaum, T. P
Wiita, P. J
Rani, B
Sokolovsky, K. V
Mohan, Prashanth
Mangalam, A
Marchili, N
Fuhrmann, L
Agudo, I
Bach, U
Bachev, R
Böttcher, M
Gabanyi, K. E
Gaur, H
Hawkins, K
Kimeridze, G. N
Kurtanidze, O. M
Kurtanidze, S. O
Lee, C.-U
Liu, X
McBreen, B
Nesci, R
Nestoras, G
Nikolashvili, M. G
Ohlert, J. M
Palma, N
Peneva, S
Pursimo, T
Semkov, E
Strigachev, A
Webb, J. R
Wiesemeyer, H
Zensus, J. A
Keywords: Galaxies: active;BL Lacertae objects: general;BL Lacertae objects: individual: S5 0716+714
Issue Date: Sep-2012
Publisher: Wiley-Blackwell
Citation: Monthly Notices of the Royal Astronomical Society, Vol. 425, No. 2, pp. 1357–1370
Abstract: We report results from a one-week multiwavelength campaign to monitor the BL Lacertae object (BL Lac) S5 0716+714 (on 2009 December 9–16). Nine ground-based telescopes at widely separated longitudes and one space-based telescope aboard the Swift satellite collected optical data. Radio data were obtained from the Effelsberg and Urumqi observatories and X-ray data from Swift. In the radio bands, the source shows rapid [∼(0.5–1.5) d] intraday variability with peak amplitudes of up to ∼10 per cent. The variability at 2.8 cm leads by about 1 d the variability at 6 and 11 cm. This time lag and more rapid variations suggest an intrinsic contribution to the source's intraday variability at 2.8 cm, while at 6 and 11 cm, interstellar scintillation (ISS) seems to predominate. Large and quasi-sinusoidal variations of ∼0.8 mag were detected in the V, R and I bands. The X-ray data (0.2–10 keV) do not reveal significant variability on a 4 d time-scale, favouring reprocessed inverse Compton over synchrotron radiation in this band. The characteristic variability time-scales in radio and optical bands are similar. A quasi-periodic variation of 0.9–1.1 d in the optical data may be present, but if so it is marginal and limited to 2.2 cycles. Cross-correlations between radio and optical bands are discussed. The lack of a strong radio–optical correlation indicates different physical causes of variability (ISS at long radio wavelengths, source intrinsic origin in the optical) and is consistent with a high jet opacity and a compact synchrotron component peaking at ≃100 GHz in an ongoing very prominent flux-density outburst. For the campaign period, we construct a quasi-simultaneous spectral energy distribution, including γ-ray data from the Fermi satellite. We obtain lower limits for the relativistic Doppler boosting of δ ≥ 12–26, which for a BL Lac-type object is remarkably high.
Description: Restricted access
ISSN: 0035-8711
Appears in Collections:IIAP Publications

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