A Tight Connection between Gamma-Ray Outbursts and Parsec-scale Jet Activity in the Quasar 3C 454.3
Strelnitski, Vladimir; Walker, Gary; McHardy, Ian M.; Schmidt, Gary D.; Smith, Paul S.; Grupe, Dirk; Agudo, Iván; Jorstad, Svetlana G.; Marscher, Alan P.; Wehrle, Ann E.; Joshi, Manasvita; MacDonald, Nicholas R.; Williamson, Karen E.; Gómez, José L.; Casadio, Carolina; Gurwell, Mark; Kopatskaya, Evgenia N.; Larionova, Elena G.; Morozova, Daria A.; Lähteenmäki, Anne; Tornikoski, Merja; Taylor, Brian W.; Larionov, Valeri M.; Nikolashvili, Maria G.; Arkharov, Arkady A.; Blinov, Dmitry A.; Blumenthal, Kelly; Chigladze, Revaz A.; Efimova, Natalia V.; Eggen, Joseph R.; Hagen-Thorn, Vladimir A.; Kimeridze, Givi N.; Konstantinova, Tatiana S.; Kurtanidze, Omar M.; Kurtanidze, Sofia O.; Larionova, Liudmilla V.; Sigua, Lorand A.; Maune, Jeremy D.; Miller, H. Richard; Molina, Sol N.; Scott, Terri; Troitsky, Ivan S.; Thum, Clemens; Sallum, Stephanie; Consiglio, Santina
United States, Russia, Spain, Finland, Georgia, United Kingdom
Abstract
We analyze the multi-frequency behavior of the quasar 3C 454.3 during three prominent γ-ray outbursts: 2009 Autumn, 2010 Spring, and 2010 Autumn. The data reveal a repeating pattern, including a triple flare structure, in the properties of each γ-ray outburst, which implies similar mechanism(s) and location for all three events. The multi-frequency behavior indicates that the lower frequency events are co-spatial with the γ-ray outbursts, although the γ-ray emission varies on the shortest timescales. We determine that the variability from UV to IR wavelengths during an outburst results from a single synchrotron component whose properties do not change significantly over the different outbursts. Despite a general increase in the degree of optical linear polarization during an outburst, the polarization drops significantly at the peak of the γ-ray event, which suggests that both shocks and turbulent processes are involved. We detect two disturbances (knots) with superluminal apparent speeds in the parsec-scale jet associated with the outbursts in 2009 Autumn and 2010 Autumn. The kinematic properties of the knots can explain the difference in amplitudes of the γ-ray events, while their millimeter-wave polarization is related to the optical polarization during the outbursts. We interpret the multi-frequency behavior within models involving either a system of standing conical shocks or magnetic reconnection events located in the parsec-scale millimeter-wave core of the jet. We argue that γ-ray outbursts with variability timescales as short as ~3 hr can occur on parsec scales if flares take place in localized regions such as turbulent cells.