Bibcode
Sitarek, J.; Sillanpää, A.; Schweizer, T.; Shore, S. N.; Schultz, C.; Scapin, V.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Saito, K.; Saito, T.; Saggion, A.; Rügamer, S.; Rico, J.; Rodriguez Garcia, J.; Ribó, M.; Rhode, W.; Reinthal, R.; Puljak, I.; Preziuso, S.; Prandini, E.; Prada Moroni, P. G.; Prada, F.; Partini, S.; Persic, M.; Paredes, J. M.; Paredes-Fortuny, X.; Paoletti, R.; Paneque, D.; Palatiello, M.; Paiano, S.; Overkemping, A.; Nowak, N.; Orito, R.; Nishijima, K.; Nilsson, K.; Niedzwiecki, A.; Nakajima, D.; Munar-Adrover, P.; Mirzoyan, R.; Moralejo, A.; Miranda, J. M.; Meucci, M.; Menzel, U.; Mazin, D.; Martínez, M.; Mariotti, M.; Marcote, B.; Maraschi, L.; Mannheim, K.; Mankuzhiyil, N.; Maneva, G.; Mallot, K.; Makariev, M.; Lozano, I.; Lorenz, E.; López-Oramas, A.; López-Coto, R.; López, M.; Lombardi, S.; Lindfors, E.; Lewandowska, N.; Lelas, D.; La Barbera, A.; Kushida, J.; Kubo, H.; Krause, J.; Konno, Y.; Kodani, K.; Knoetig, M. L.; Kellermann, H.; Kadenius, V.; Idec, W.; Hrupec, D.; Hose, J.; Hildebrand, D.; Herrero, A.; Hadasch, D.; Gozzini, S. R.; Godinovic, N.; González Muñoz, A.; Giavitto, G.; Gaug, M.; Garrido Terrats, D.; Garczarczyk, M.; García López, R. J.; Fruck, C.; Frantzen, K.; Font, L.; Fonseca, M. V.; Farina, E.; Ferenc, D.; Elsaesser, D.; Eisenacher, D.; Doro, M.; Einecke, S.; Dorner, D.; Dominis Prester, D.; Domínguez, A.; Doert, M. et al.
Bibliographical reference
Astronomy and Astrophysics, Volume 567, id.A41, 14 pp.
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7
2014
Journal
Citations
39
Refereed citations
34
Description
Aims: We study the multifrequency emission and spectral
properties of the quasar3C 279 aimed at identifying
the radiation processes taking place in the source. Methods: We
observed 3C 279 in very-high-energy (VHE, E> 100
GeV) γ-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> 100 MeV)
γ-rays from Fermi-LAT; in X-rays from RXTE; in the optical from
the KVA telescope; and in the radio at 43 GHz, 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 γ-rays.
The MAGIC observations did not yield a significant detection. The
derived upper limits are in agreement with the extrapolation of the HE
γ-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 γ-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
γ-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
γ-ray data, assuming an emission component inside the broad line
region with size R = 1.1 × 1016 cm and magnetic field B
= 1.45 G responsible for the high-energy emission, and another one
outside the broad line region and the infrared torus (R = 1.5 ×
1017 cm and B = 0.8 G) causing the optical and low-energy
emission. We also study the optical polarisation in detail and interpret
it with a bent trajectory model.
Related projects
Particle Astrophysics
The MAGIC Collaboration is integrated by 20 research institutes and university departments from Armenia, Bulgaria, Finland, Germany, Italy, Poland, Spain, Switzerland and USA. The collaboration comprises two 17m diameter telescopes, located at the Roque de los Muchachos Observatory, designed to measure the Cherenkov radiation associated with
Ramón
García López