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Title: The outburst of the blazar S4 0954+658 in 2011 March-April

We present the results of optical (R-band) photometric and polarimetric monitoring and Very Long Baseline Array imaging of the blazar S4 0954+658, along with Fermi γ-ray data during a multi-waveband outburst in 2011 March-April. After a faint state with a brightness level R ∼ 17.6 mag registered in the first half of 2011 January, the optical brightness of the source started to rise and reached ∼14.8 mag during the middle of March, showing flare-like behavior. The most spectacular case of intranight variability was observed during the night of 2011 March 9, when the blazar brightened by ∼0.7 mag within 7 hr. During the rise of the flux, the position angle of the optical polarization rotated smoothly over more than 300°. At the same time, within 1σ uncertainty, a new superluminal knot appeared with an apparent speed of 19.0 ± 0.3c. We have very strong evidence that this knot is associated with the multi-waveband outburst in 2011 March-April. We also analyze the multi-frequency behavior of S4 0954+658 during a number of minor outbursts from 2008 August to 2012 April. We find some evidence of connections between at least two additional superluminal ejecta and near-simultaneous optical flares.
Authors:
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  1. Astronomical Institute of St. Petersburg State University, Universitetsky Pr. 28, Petrodvorets, 198504 St. Petersburg (Russian Federation)
  2. Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215-1401 (United States)
  3. Instituto de Astrofísica de Andalucía, CSIC, Apartado 3004, E-18080 Granada (Spain)
  4. Aalto University Metsähovi Radio Observatory, Metsähovintie 114,FI-02540 Kylmälä (Finland)
  5. Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom)
Publication Date:
OSTI Identifier:
22342273
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 148; Journal Issue: 3; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BL LACERTAE OBJECTS; BRIGHTNESS; GALAXIES; PHOTOMETRY; POLARIZATION; RISE; STARS; VELOCITY; VISIBLE RADIATION