Multi-Frequency Monitoring of the Flat Spectrum Radio Quasar PKS 1222+216 in 2008-2015

DOI: 
10.3390/galaxies4040072
Publication date: 
28/11/2016
Main author: 
Troitskiy, Ivan
IAA authors: 
Agudo, Ivan
Authors: 
Troitskiy, Ivan; Morozova, Daria; Jorstad, Svetlana; Larionov, Valery; Marscher, Alan; Agudo, Ivan; Blinov, Dmitry; Smith, Paul; Troitskaya, Yuliya
Journal: 
Galaxies
Refereed: 
Yes
Publication type: 
Article
Volume: 
4
Pages: 
72
Issue: 
4
Abstract: 
<p>We analyze the broadband activity of the flat spectrum radio quasar PKS 1222+216 from 2008 to 2015 using multi-frequency monitoring which involves <i>γ</i>-ray data from the <i>Fermi</i> Large Area Telescope, total intensity and linear polarization observations from different optical telescopes in R band, and imaging of the inner jet structure with the Very Long Baseline Array (VLBA) at 43 GHz. During the observations, the source showed several dramatic flares at <i>γ</i> rays and optical bands, with the rising branch of a <i>γ</i>-ray flare accompanied by a rapid rotation of the polarization position angle (EVPA), a fast increase of the degree of polarization in the optical band, brightening of the VLBI core, and appearance of a new superluminal component in the parsec-scale jet. The rapid variability of the optical linear polarization may be explained by a strong turbulence in the jet plasma. We find a correlation between the <i>γ</i> rays, optical R band, and 43 GHz variability on a long-term scale (months and years), and a good general alignment between EVPAs in R band and at 43 GHz, while the correlation between short-term variations (days and weeks) is weaker. Synchronous activity across the bands supports the idea that the emission regions responsible for the <i>γ</i>-ray and optical flares are co-spatial and located in the vicinity of the mm-wave core of the parsec-scale jet. However, these connections do not completely explain the challenging behaviour of PKS 1222+216, since there are some <i>γ</i>-ray flares which are not accompanied by jet events, and vice versa. We need a continuation of multi-frequency monitoring along with high resolution imaging of the parsec-scale jet to understand in detail the origin of high energy emission in blazars.</p>
Database: 
ADS
URL: 
http://www.mdpi.com/2075-4434/4/4/72
ADS Bibcode: 
2016Galax...4...72T
Keywords: 
blazars; jets; VLBA; polarization