Bibcode
Aleksić, J.; Alvarez, E. A.; Antonelli, L. A.; Antoranz, P.; Asensio, M.; Backes, M.; Barrio, J. A.; Bastieri, D.; Becerra-González, J.; Bednarek, W.; Berdyugin, A.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnoli, G.; Borla Tridon, D.; Braun, I.; Bretz, T.; Cañellas, A.; Carmona, E.; Carosi, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Cea del Pozo, E.; De Lotto, B.; Delgado-Mendez, C.; Diago-Ortega, A.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Elsaesser, D.; Ferenc, D.; Fonseca, M. V.; Font, L.; Fruck, C.; García-López, R. J.; Garczarczyk, M.; Garrido, D.; Giavitto, G.; Godinović, N.; Hadasch, D.; Häfner, D.; Herrero, A.; Hildebrand, D.; Höhne-Mönch, D.; Hose, J.; Hrupec, D.; Huber, B.; Jogler, T.; Kellermann, H.; Klepser, S.; Krähenbühl, T.; Krause, J.; La Barbera, A.; Lelas, D.; Leonardo, E.; Lindfors, E.; Lombardi, S.; López, A.; López, M.; Lorenz, E.; Makariev, M.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Miyamoto, H.; Moldón, J.; Moralejo, A.; Munar-Adrover, P.; Nieto, D.; Nilsson, K.; Orito, R.; Oya, I.; Paneque, D.; Paoletti, R.; Pardo, S.; Paredes, J. M.; Partini, S.; Pasanen, M.; Pauss, F.; Perez-Torres, M. A. et al.
Bibliographical reference
Astronomy and Astrophysics, Volume 542, id.A100
Advertised on:
6
2012
Journal
Citations
66
Refereed citations
60
Description
Context. The blazar Markarian 421 is one of the brightest TeV gamma-ray
sources of the northern sky. From December 2007 until June 2008 it was
intensively observed in the very high energy (VHE, E > 100 GeV) band
by the single-dish Major Atmospheric Gamma-ray Imaging Cherenkov
telescope (MAGIC-I). Aims: We aimed to measure the physical
parameters of the emitting region of the blazar jet during active
states. Methods: We performed a dense monitoring of the source in
VHE with MAGIC-I, and also collected complementary data in soft X-rays
and optical-UV bands; then, we modeled the spectral energy distributions
(SED) derived from simultaneous multi-wavelength data within the
synchrotron self-Compton (SSC) framework. Results: The source
showed intense and prolonged γ-ray activity during the whole
period, with integral fluxes (E > 200 GeV) seldom below the level of
the Crab Nebula, and up to 3.6 times this value. Eight datasets of
simultaneous optical-UV (KVA, Swift/UVOT), soft X-ray (Swift/XRT) and
MAGIC-I VHE data were obtained during different outburst phases. The
data constrain the physical parameters of the jet, once the spectral
energy distributions obtained are interpreted within the framework of a
single-zone SSC leptonic model. Conclusions: The main outcome of
the study is that within the homogeneous model high Doppler factors (40
≤ δ ≤ 80) are needed to reproduce the observed SED; but this
model cannot explain the observed short time-scale variability, while it
can be argued that inhomogeneous models could allow for less extreme
Doppler factors, more intense magnetic fields and shorter electron
cooling times compatible with hour or sub-hour scale variability.
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