Next Article in Journal
Galaxy Cluster Outskirts from the Thermal SZ and Non-Thermal Synchrotron Link
Next Article in Special Issue
Emission Knots and Polarization Swings of Swinging Jets
Previous Article in Journal
Studying the Effect of Shock Obliquity on the γ-ray and Diffuse Radio Emission in Galaxy Clusters
Previous Article in Special Issue
Direct Imaging of a Toroidal Magnetic Field in the Inner Jet of NRAO 150
Open AccessArticle

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

Astronomical Institute, St. Petersburg State University, Universitetsky Prospekt, 28, Peterhof, St. Petersburg 198504, Russia
Institute for Astrophysical Research, Boston University, 725 Commonwealth Ave., Boston, MA 02215, USA
Instituto de Astrofisíca de Andalucía, CSIC, Glorieta de la Astronomía, Granada E-18008, Spain
Department of Physics, Institute for Plasma Physics, University of Crete, Heraklion GR-71003, Greece
Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USA
Author to whom correspondence should be addressed.
Academic Editor: Emilio Elizalde
Galaxies 2016, 4(4), 72;
Received: 15 July 2016 / Revised: 20 November 2016 / Accepted: 21 November 2016 / Published: 28 November 2016
(This article belongs to the Special Issue Blazars through Sharp Multi-wavelength Eyes)
We analyze the broadband activity of the flat spectrum radio quasar PKS 1222+216 from 2008 to 2015 using multi-frequency monitoring which involves γ-ray data from the Fermi 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 γ rays and optical bands, with the rising branch of a γ-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 γ 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 γ-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 γ-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. View Full-Text
Keywords: blazars; jets; VLBA; polarization blazars; jets; VLBA; polarization
Show Figures

Figure 1

MDPI and ACS Style

Troitskiy, I.; Morozova, D.; Jorstad, S.; Larionov, V.; Marscher, A.; Agudo, I.; Blinov, D.; Smith, P.; Troitskaya, Y. Multi-Frequency Monitoring of the Flat Spectrum Radio Quasar PKS 1222+216 in 2008–2015. Galaxies 2016, 4, 72.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Back to TopTop