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MAGIC observations and multifrequency properties of the flat spectrum radio quasar 3C 279 in 2011

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Antoranz Canales, Pedro and Barrio Uña, Juan Abel and Contreras González, José Luis and Fonseca González, Mª Victoria and López Moya, Marcos and Miranda Pantoja, José Miguel and Satalecka, Konstanzja and Scapin, Valeria (2014) MAGIC observations and multifrequency properties of the flat spectrum radio quasar 3C 279 in 2011. Astronomy and astrophysics, 567 . ISSN 0004-6361

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Official URL: http://dx.doi.org/10.1051/0004-6361/201323036


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Abstract

Aims. We study the multifrequency emission and spectral properties of the quasar 3C 279 aimed at identifying the radiation processes taking place in the source.
Methods. We observed 3C 279 in very-high-energy (VHE, E > 100GeV) gamma-rays, with the MAGIC telescopes during 2011, for the first time in stereoscopic mode. We combined these measurements with observations at other energy bands: in high-energy (HE, E > 100MeV) gamma-rays from Fermi–LAT; in X-rays from RXTE; in the optical from the KVA telescope; and in the radio at 43GHz, 37 GHz, and 15 GHz from the VLBA, Metsähovi, and OVRO radio telescopes - along with optical polarisation measurements from the KVA and Liverpool telescopes. We examined the corresponding light curves and broadband spectral energy distribution and we compared the multifrequency properties of 3C 279 at the epoch of the MAGIC observations with those inferred from historical observations.
Results. During the MAGIC observations (2011 February 8 to April 11) 3C 279 was in a low state in optical, X-ray, and gamma-rays. The MAGIC observations did not yield a significant detection. The derived upper limits are in agreement with the extrapolation of the HE gamma-ray spectrum, corrected for EBL absorption, from Fermi–LAT. The second part of the MAGIC observations in 2011 was triggered by a high-activity state in the optical and gamma-ray bands. During the optical outburst the optical electric vector position angle (EVPA) showed a rotation of ∼ 180◦. Unlike previous cases, there was no simultaneous rotation of the 43 GHz radio polarisation angle. No VHE gamma-rays were detected by MAGIC, and the derived upper limits suggest the presence of a spectral break or curvature between the Fermi–LAT and MAGIC bands. The combined upper limits are the strongest derived to date for the source at VHE and below the level of the previously detected flux by a factor of ∼ 2. Radiation models that include synchrotron and inverse Compton emissions match the optical to gamma-ray data, assuming an emission component inside the broad line region with size R = 1.1 × 10^(16) cm and magnetic field B = 1.45G responsible for the high-energy emission, and another one outside the broad line region and the infrared torus (R = 1.5 × 10^(17) cm and B = 0.8G) causing the optical and low-energy emission. We also study the optical polarisation in detail and interpret it with a bent trajectory model.


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© ESO 2014. We would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The support of the German BMBF and MPG, the Italian INFN, the Swiss National Fund SNF, and the Spanish MICINN is gratefully acknowledged. This work was also supported by the CPAN CSD2007-00042 and MultiDark CSD2009-00064 projects of the Spanish Consolider-Ingenio 2010 programme, by grant 127740 of the Academy of Finland, by the DFG Cluster of Excellence “Origin and Structure of the Universe”, by the Croatian Science Foundation Project 09/176, by the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, and by the Polish MNiSzW grant 745/N-HESS-MAGIC/2010/0.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’Energie Atomique and the Centre National de la Recherche Scientifique / Institut National de Physique Nucléaire 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, the Swedish Research Council and the 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’´Etudes Spatiales in France. The OVRO 40-m monitoring program is supported in part by NASA grants NNX08AW31G and NNX11A043G, and NSF grants AST-0808050 and AST-1109911. The Metsähovi team acknowledges the support from the Academy of Finland to our observing projects (numbers 212656, 210338, 121148, and others).

Uncontrolled Keywords:Active galactic nuclei; Large-area telescope; Gamma-ray emission; PKS 1510-089; Multiwavelength observations; Relativistic jet; Blazar 3C-279; Inner jet; X-ray; Variability.
Subjects:Sciences > Physics > Electricity
Sciences > Physics > Electronics
Sciences > Physics > Nuclear physics
ID Code:29186
Deposited On:12 Mar 2015 10:27
Last Modified:10 Dec 2018 14:57

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