@article{20e42e4525ef421ab9fdc271f0071ccd,
title = "Exploring the Connection between Parsec-scale Jet Activity and Broadband Outbursts in 3C 279",
abstract = "We use a combination of high-resolution very long baseline interferometry (VLBI) radio and multiwavelength flux density and polarization observations to constrain the physics of the dissipation mechanism powering the broadband flares in 3C 279 during an episode of extreme flaring activity in 2013-2014. Six bright flares superimposed on a long-term outburst are detected at γ-ray energies. Four of the flares have optical and radio counterparts. The two modes of flaring activity (faster flares sitting on top of a long-term outburst) present at radio, optical, and γ-ray frequencies are missing in X-rays. X-ray counterparts are only observed for two flares. The first three flares are accompanied by ejection of a new VLBI component (NC2), suggesting the 43 GHz VLBI core as the site of energy dissipation. Another new component, NC3, is ejected after the last three flares, which suggests that the emission is produced upstream from the core (closer to the black hole). The study therefore indicates multiple sites of energy dissipation in the source. An anticorrelation is detected between the optical percentage polarization (PP) and optical/γ-ray flux variations, while the PP has a positive correlation with optical/γ-ray spectral indices. Given that the mean polarization is inversely proportional to the number of cells in the emission region, the PP versus optical/γ-ray anticorrelation could be due to more active cells during the outburst than at other times. In addition to the turbulent component, our analysis suggests the presence of a combined turbulent and ordered magnetic field, with the ordered component transverse to the jet axis.",
keywords = "galaxies: active, galaxies: jets, gamma rays: galaxies, quasars: individual (3C 279), radio continuum: galaxies",
author = "B. Rani and Jorstad, {S. G.} and Marscher, {A. P.} and I. Agudo and Sokolovsky, {K. V.} and Larionov, {V. M.} and P. Smith and Mosunova, {D. A.} and Borman, {G. A.} and Grishina, {T. S.} and Kopatskaya, {E. N.} and Mokrushina, {A. A.} and Morozova, {D. A.} and Savchenko, {S. S.} and Troitskaya, {Yu V.} and Troitsky, {I. S.} and C. Thum and Molina, {S. N.} and C. Casadio",
note = "Funding Information: The Fermi/LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT, as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States; the Commissariat {\`a} l{\textquoteright}Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucl{\'e}aire et de Physique des Particules in France; the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy; the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK), and Japan Aerospace Exploration Agency (JAXA) in Japan; and the K.A.Wallenberg Foundation, Swedish Research Council, and Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d{\textquoteright}{\'E}tudes Spatiales in France. This work was performed in part under DOE Contract DE-AC02-76SF00515. Funding Information: This research was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by the Universities Space Research Association through a contract with NASA. This study makes use of 43 GHz VLBA data from the VLBA-BU Blazar Monitoring Program (VLBA-BU-BLAZAR;http://www.bu. edu/blazars/VLBAproject.html), funded by NASA through the Fermi Guest Investigator Program. The VLBA is an instrument of the Long Baseline Observatory. The Long Baseline Observatory is a facility of the National Science Foundation operated by Associated Universities, Inc. The BU group acknowledges support from US National Science Foundation grant AST-1615796. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. This research was supported by an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by the Universities Space Research Association through a contract with NASA. KS is supported by the Russian Science Foundation grant 16-12-10481. The St.Petersburg University team acknowledges support from Russian Science Foundation grant 17-12-01029. This research has made use of data from the OVRO 40 m monitoring program (Richards et al. 2011), which is supported in part by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G and NSF grants AST-0808050 and AST-1109911. IA acknowledges support by a Ram{\'o}n y Cajal grant of the Ministerio de Econom{\'i}a, Industria, y Competitividad (MINECO) of Spain. Acquisition and reduction of the POLAMI data was supported in part by MINECO through grants AYA2010-14844, AYA2013-40825-P, and AYA2016-80889-P and by the Regional Government of Andaluc{\'i}a through grant P09-FQM-4784. The POLAMI observations were carried out at the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). BR acknowledges the help of Roopesh Ojha, Marcello Giroletti, and Dave Thompson for fruitful discussions and comments that improved the manuscript. Publisher Copyright: {\textcopyright} 2018. The American Astronomical Society. All rights reserved.",
year = "2018",
month = may,
day = "10",
doi = "10.3847/1538-4357/aab785",
language = "English (US)",
volume = "858",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2",
}