2011/05/19 by Ivan Agudo, I. Agudo, Alan P. Marscher +69 · 132 citations
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #BL Lac object #Blazar #Galaxy #Gamma ray #Knot (papermaking) #Light curve #Line-of-sight #Linear polarization #Millimeter #Optics #Physics #Polarization (electrochemistry) #Radio Astronomy Observations and Technology #Superluminal motion #Supermassive black hole #Very Long Baseline Array #Very-long-baseline interferometry #Wavelength #astro-ph.CO #astro-ph.HE
paper · pdf · doi:10.1088/2041-8205/735/1/l10
published in The Astrophysical Journal Letters 735(1), L10 (IOP Publishing) · Accepted for Publication in the Astrophysical Journal Letters. 7 pages (including 5 figures). Minor corrections with regard to previous version, as proposed by the referee
arxiv created 2011/05/19 · openalex publication_date 2011/06/06 · arxiv updated 2015/05/28 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and γ-ray wavelengths of the BL Lacertae object AO 0235+164. We analyze the timing of multi-waveband variations in the flux and linear polarization, as well as changes in Very Long Baseline Array images at λ = 7 mm with ∼0.15 milliarcsec resolution. The association of the events at different wavebands is confirmed at high statistical significance by probability arguments and Monte Carlo simulations. A series of sharp peaks in optical linear polarization, as well as a pronounced maximum in the 7 mm polarization of a superluminal jet knot, indicate rapid fluctuations in the degree of ordering of the magnetic field. These results lead us to conclude that the outburst occurred in the jet both in the quasi-stationary "core" and in the superluminal knot, both parsecs downstream of the supermassive black hole. We interpret the outburst as a consequence of the propagation of a disturbance, elongated along the line of sight by light-travel time delays, that passes through a standing recollimation shock in the core and propagates down the jet to create the superluminal knot. The multi-wavelength light curves vary together on long timescales (months/years), but the correspondence is poorer on shorter timescales. This, as well as the variability of the polarization and the dual location of the outburst, agrees with the expectations of a multi-zone emission model in which turbulence plays a major role in modulating the synchrotron and inverse Compton fluxes.