2010/03/10 by Mahito Sasada, Makoto Uemura, Akira Arai +12 · 37 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #BL Lac object #Blazar #Clockwise #Cold Fusion and Nuclear Reactions #Flare #Polarimetry #Polarization (electrochemistry) #Position angle #Rotation (mathematics) #Solar and Space Plasma Dynamics #astro-ph.CO #astro-ph.HE
paper · pdf · doi:10.1093/pasj/62.3.645
published in Publications of the Astronomical Society of Japan 62(3), 645-652 (Oxford University Press) · Accepted for publication in PASJ. 8 pages, 8 figures
arxiv created 2010/03/10 · openalex publication_date 2010/06/25 · arxiv updated 2015/05/18 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Abstract We report on optical—near-infrared photopolarimetric observations of a blazar 3C 454.3 over 200 d. The object experienced an optical outburst in 2007 July. This outburst was followed by a short state fainter than V = 15.2 mag, lasting ∼ 25 d. The object then entered an active state during which we observed short flares having a timescale of 3–10 d. The object showed two types of features in the color–magnitude relationship. One was a “bluer-when-brighter” trend in the outburst state, and the other was a “redder-when-brighter” trend in the faint state. These two types of features suggest a contribution of thermal emission to the observed flux, as suspected in previous studies. Our polarimetric observation detected two episodes of rotation of the polarization vector. The first one was a counterclockwise rotation in the QU plane during the outburst state. After this rotation event of the polarization vector, the object entered a rapidly fading stage. The second one was seen in a series of flares during the active state. Each flare had a specific position angle of polarization, which apparently rotated clockwise from the first to the last flares. Thus, the object exhibited rotations of the polarization vector in opposite directions. We estimated a decay timescale of the short flares during the active state, and then calculated an upper limit of the strength of the magnetic field, B = 0.2 G, assuming a typical beaming factor of blazars, δ = 20. This upper limit of B is smaller than those previously estimated from spectral analysis.