Bibcode
Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Arcaro, C.; Babić, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Berti, A.; Bhattacharyya, W.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Carosi, R.; Carosi, A.; Chatterjee, A.; Colak, M.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Cumani, P.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Oña Wilhelmi, E.; Di Pierro, F.; Doert, M.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher Glawion, D.; Elsaesser, D.; Engelkemeier, M.; Fallah Ramazani, V.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Gaug, M.; Giammaria, P.; Godinović, N.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hassan, T.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Inada, T.; Ishio, K.; Konno, Y.; Kubo, H.; Kushida, J.; Kuveždić, D.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; Maggio, C.; Majumdar, P.; Makariev, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Minev, M.; Mirzoyan, R.; Moralejo, A.; Moreno, V.; Moretti, E.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Ninci, D.; Nishijima, K.; Noda, K.; Nogués, L. et al.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 472, Issue 3, p.2956-2962
Advertised on:
12
2017
Citations
76
Refereed citations
61
Description
It is widely believed that the bulk of the Galactic cosmic rays is
accelerated in supernova remnants (SNRs). However, no observational
evidence of the presence of particles of PeV energies in SNRs has yet
been found. The young historical SNR Cassiopeia A (Cas A) appears as one
of the best candidates to study acceleration processes. Between 2014
December and 2016 October, we observed Cas A with the MAGIC telescopes,
accumulating 158 h of good quality data. We derived the spectrum of the
source from 100 GeV to 10 TeV. We also analysed ∼8 yr of Fermi-LAT
to obtain the spectral shape between 60 MeV and 500 GeV. The spectra
measured by the LAT and MAGIC telescopes are compatible within the
errors and show a clear turn-off (4.6σ) at the highest energies,
which can be described with an exponential cut-off at E_c =
3.5(^{+1.6}_{-1.0})_{stat} (^{+0.8}_{-0.9})_{sys} TeV. The gamma-ray
emission from 60 MeV to 10 TeV can be attributed to a population of
high-energy protons with a spectral index of ∼2.2 and an energy
cut-off at ∼10 TeV. This result indicates that Cas A is not
contributing to the high energy (∼PeV) cosmic ray sea in a
significant manner at the present moment. A one-zone leptonic model
fails to reproduce by itself the multiwavelength spectral energy
distribution. Besides, if a non-negligible fraction of the flux seen by
MAGIC is produced by leptons, the radiation should be emitted in a
region with a low magnetic field (B⪅180 μG) like in the
reverse shock.
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