Bibcode
Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Carreto Fidalgo, D.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; Delgado Mendez, C.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher, D.; Elsaesser, D.; Farina, E.; Ferenc, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giavitto, G.; Godinović, N.; González Muñoz, A.; Gozzini, S. R.; Hadamek, A.; Hadasch, D.; Herrero, A.; Hildebrand, D.; Hose, J.; Hrupec, D.; Idec, W.; Kadenius, V.; Kellermann, H.; Knoetig, M. L.; Krause, J.; Kushida, J.; La Barbera, A.; Lelas, D.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López, M.; López-Coto, R.; López-Oramas, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Niedzwiecki, A.; Nilsson, K.; Nowak, N.; Orito, R.; Overkemping, A.; Paiano, S. et al.
Bibliographical reference
Astronomy and Astrophysics, Volume 564, id.A5, 13 pp.
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4
2014
Journal
Citations
60
Refereed citations
47
Description
Aims: The radio galaxy NGC 1275, recently
identified as a very high energy (VHE, >100 GeV) γ-ray emitter
by MAGIC, is one of the few non-blazar active galactic nuclei detected
in the VHE regime. The purpose of this work is to better understand the
origin of the γ-ray emission and locate it within the galaxy. Methods: We studied contemporaneous multifrequency observations of
NGC 1275 and modeled the overall spectral energy
distribution. We analyzed unpublished MAGIC observations carried out
between October 2009 and February 2010, and the previously published
observations taken between August 2010 and February 2011. We studied the
multiband variability and correlations by analyzing data of Fermi-LAT in
the 100 MeV-100 GeV energy band, as well as Chandra (X-ray), KVA
(optical), and MOJAVE (radio) data taken during the same period.
Results: Using customized Monte Carlo simulations corresponding to early
MAGIC stereoscopic data, we detect NGC 1275 also in
the earlier MAGIC campaign. The flux level and energy spectra are
similar to the results of the second campaign. The monthly light curve
above 100 GeV shows a hint of variability at the 3.6σ level. In
the Fermi-LAT band, both flux and spectral shape variabilities are
reported. The optical light curve is also variable and shows a clear
correlation with the γ-ray flux above 100 MeV. In radio, three
compact components are resolved in the innermost part of the jet. One of
these components shows a similar trend as the Fermi-LAT and KVA light
curves. The γ-ray spectra measured simultaneously with MAGIC and
Fermi-LAT from 100 MeV to 650 GeV can be well fitted either by a
log-parabola or by a power-law with a subexponential cutoff for the two
observation campaigns. A single-zone synchrotron-self-Compton model,
with an electron spectrum following a power-law with an exponential
cutoff, can explain the broadband spectral energy distribution and the
multifrequency behavior of the source. However, this model suggests an
untypical low bulk-Lorentz factor or a velocity alignment closer to the
line of sight than the parsec-scale radio jet.
Related projects

Particle Astrophysics
The members of the Particle Astrophysics Group of the IAC participate actively in three large international collaborations of high-energy astrophysics: AMS-02 (Alpha Magnetic Spectrometer), the Cherenkov radiation telescopes MAGIC I and II and the Cherenkov Telescope Array Observatory ( CTAO). We also participate in the ASTRI mini-array, the gamma
Mónica Luisa
Vázquez Acosta