Prominent outburst of the blazar CTA 102 in 2012

Larionov, V. M.; Blinov, D.; Jorstad, S. G.; Marscher, A. P.; Villata, M.; Raiteri, C. M.; Agudo, I.; Smith, Paul S.; Morozova, D. A.; Troitsky, I. S.; Clemens, D. P.

doi:10.1051/epjconf/20136104019

Cited by 12 publications

(12 citation statements)

References 18 publications

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“…Hints that a helical magnetic field also exists in the innermost regions of the jets come from polarization observations at optical frequencies. The optical electric vector position angles (EVPAs) have been observed rotating in coincidence with a multi-wavelength flaring event that occurred in 2012 and that also coincided with the ejection of a new superluminal component from the radio core (Larionov et al 2013;Casadio et al 2015). Evidence for a physical connection between EVPA rotations and γ-ray flares has been found in a number of other sources (e.g., Marscher et al 2010).…”

Section: Introductionmentioning

confidence: 93%

The magnetic field structure in CTA 102 from high-resolution mm-VLBI observations during the flaring state in 2016–2017

Casadio

Marscher

Jorstad

et al. 2019

A&A

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Context. Investigating the magnetic field structure in the innermost regions of relativistic jets is fundamental to understanding the crucial physical processes giving rise to jet formation, as well as to their extraordinary radiation output up to γ-ray energies. Aims. We study the magnetic field structure of the quasar CTA 102 with 3 and 7 mm VLBI polarimetric observations, reaching an unprecedented resolution (∼50 µas). We also investigate the variability and physical processes occurring in the source during the observing period, which coincides with a very active state of the source over the entire electromagnetic spectrum. Methods. We perform the Faraday rotation analysis using 3 and 7 mm data and we compare the obtained rotation measure (RM) map with the polarization evolution in 7 mm VLBA images. We study the kinematics and variability at 7 mm and infer the physical parameters associated with variability. From the analysis of γ-ray and X-ray data, we compute a minimum Doppler factor value required to explain the observed high-energy emission.Results. Faraday rotation analysis shows a gradient in RM with a maximum value of ∼6×10 4 rad/m 2 and intrinsic electric vector position angles (EVPAs) oriented around the centroid of the core, suggesting the presence of large-scale helical magnetic fields. Such a magnetic field structure is also visible in 7 mm images when a new superluminal component is crossing the core region. The 7 mm EVPA orientation is different when the component is exiting the core or crossing a stationary feature at ∼0.1 mas. The interaction between the superluminal component and a recollimation shock at ∼0.1 mas could have triggered the multi-wavelength flares. The variability Doppler factor associated with such an interaction is large enough to explain the high-energy emission and the remarkable optical flare occurred very close in time.

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Section: Introductionmentioning

confidence: 93%

The magnetic field structure in CTA 102 from high-resolution mm-VLBI observations during the flaring state in 2016–2017

Casadio

Marscher

Jorstad

et al. 2019

A&A

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“…The remaining colors show c consistent with zero. The observed nonlinearity, particular in the 2013-flare, can be interpreted as a viewing angle change of a discrete moving emission region (Papadakis et al 2007;Larionov et al 2010Larionov et al , 2013a. Enhanced Doppler beaming caused by a viewing angle change will increase the flux across bands while at the same time shifting the intrinsic spectrum towards higher frequencies.…”

Section: Spectral Analysismentioning

confidence: 99%

Two Flares with One Shock: The Interesting Case of 3C 454.3

Liodakis

Blinov

Jorstad

et al. 2020

ApJ

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“…In this paper we analyse the largest outburst of CTA 102 to date at optical and γ-ray bands (Larionov et al 2012). A preliminary analysis of our data collected through fall 2012 is reported in Larionov et al (2013a); in the present paper we extend the data set up to the end of 2015. In § 2 we describe our observational data and their reduction; in § 3.1 we analyse the colour variability of CTA 102 and evolution of its spectral energy distribution (SED); § 3.2 deals with γ -optical correlations.…”

Section: Introductionmentioning

confidence: 99%

Exceptional outburst of the blazar CTA 102 in 2012: the GASP–WEBT campaign and its extension

Larionov

Villata

Raiteri

et al. 2016

Mon. Not. R. Astron. Soc.

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After several years of quiescence, the blazar CTA 102 underwent an exceptional outburst in 2012 September-October. The flare was tracked from γ -ray to near-infrared (NIR) frequencies, including Fermi and Swift data as well as photometric and polarimetric data from several observatories. An intensive Glast-Agile support programme of the Whole Earth Blazar Telescope (GASP-WEBT) collaboration campaign in optical and NIR bands, with an addition of previously unpublished archival data and extension through fall 2015, allows comparison of this outburst with the previous activity period of this blazar in [2004][2005]. We find remarkable similarity between the optical and γ -ray behaviour of CTA 102 during the outburst, with a time lag between the two light curves of ≈1 h, indicative of cospatiality of the optical and γ -ray emission regions. The relation between the γ -ray and optical fluxes is consistent with the synchrotron self-Compton (SSC) mechanism, with a quadratic dependence of the SSC γ -ray flux on the synchrotron optical flux evident in the post-outburst stage. However, the γ -ray/optical relationship is linear during the outburst; we attribute this to changes in the Doppler factor. A strong harder-when-brighter spectral dependence is seen both the in γ -ray and optical non-thermal emission. This hardening can be explained by convexity of the UV-NIR spectrum that moves to higher frequencies owing to an increased Doppler shift as the viewing angle decreases during the outburst stage. The overall pattern of Stokes parameter variations agrees with a model of a radiating blob or shock wave that moves along a helical path down the jet.

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Prominent outburst of the blazar CTA 102 in 2012

Cited by 12 publications

References 18 publications

The magnetic field structure in CTA 102 from high-resolution mm-VLBI observations during the flaring state in 2016–2017

The magnetic field structure in CTA 102 from high-resolution mm-VLBI observations during the flaring state in 2016–2017

Two Flares with One Shock: The Interesting Case of 3C 454.3

Exceptional outburst of the blazar CTA 102 in 2012: the GASP–WEBT campaign and its extension

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