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A multi-wavelength polarimetric study of the Blazar CTA 102 during a gamma-ray flare in 2012


Casadio, C and Gomez, JL and Jorstad, SG and Marscher, AP and Larionov, VM and Smith, PS and Gurwell, MA and Lahteenmaki, A and Agudo, I and Molina, SN and Bala, V and Joshi, M and Taylor, B and Williamson, KE and Arkharov, AA and Blinov, DA and Borman, GA and Di Paola, A and Grishina, TS and Hagen-Thorn, VA and Itoh, R and Kopatskaya, EN and Larionova, EG and Larionova, LV and Morozova, DA and Rastorgueva-Foi, E and Sergeev, SG and Tornikoski, M and Troitsky, IS and Thum, C and Wiesemeyer, H, A multi-wavelength polarimetric study of the Blazar CTA 102 during a gamma-ray flare in 2012, Astrophysical Journal, 813, (1) Article 51. ISSN 0004-637X (2015) [Refereed Article]


Copyright Statement

© 2015. The American Astronomical Society. All rights reserved.

DOI: doi:10.1088/0004-637X/813/1/51


We perform a multi-wavelength polarimetric study of the quasar CTA 102 during an extraordinarily bright γ-ray outburst detected by the Fermi Large Area Telescope in 2012 September–October when the source reached a flux of F>100 MeV = 5.2 ± 0.4 × 10−6 photons cm−2 s−1. At the same time, the source displayed an unprecedented optical and near-infrared (near-IR) outburst. We study the evolution of the parsec-scale jet with ultra-high angular resolution through a sequence of 80 total and polarized intensity Very Long Baseline Array images at 43 GHz, covering the observing period from 2007 June to 2014 June. We find that the γ-ray outburst is coincident with flares at all the other frequencies and is related to the passage of a new superluminal knot through the radio core. The powerful γ-ray emission is associated with a change in direction of the jet, which became oriented more closely to our line of sight (θ ~ 1fdg2) during the ejection of the knot and the γ-ray outburst. During the flare, the optical polarized emission displays intra-day variability and a clear clockwise rotation of electric vector position angles (EVPAs), which we associate with the path followed by the knot as it moves along helical magnetic field lines, although a random walk of the EVPA caused by a turbulent magnetic field cannot be ruled out. We locate the γ-ray outburst a short distance downstream of the radio core, parsecs from the black hole. This suggests that synchrotron self-Compton scattering of NIR to ultraviolet photons is the probable mechanism for the γ-ray production.

Item Details

Item Type:Refereed Article
Keywords:galaxies: active, galaxies: jets, quasars: individual (CTA 102), techniques: interferometric, techniques: photometric, techniques: polarimetric
Research Division:Physical Sciences
Research Group:Astronomical sciences
Research Field:Cosmology and extragalactic astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the physical sciences
UTAS Author:Rastorgueva-Foi, E (Dr Elizaveta Rastorgueva-Foi)
ID Code:105939
Year Published:2015
Web of Science® Times Cited:41
Deposited By:Mathematics and Physics
Deposited On:2016-01-20
Last Modified:2016-06-01
Downloads:249 View Download Statistics

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