A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
A cut-off in the TeV gamma-ray spectrum of the SNR Cassiopeia A
Tekijät: Ahnen ML, Ansoldi S, Antonelli LA, Arcaro C, Babic A, Banerjee B, Bangale P, de Almeida UB, Barrio JA, Gonzalez JB, 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 JL, Cortina J, Covino S, Cumani P, Da Vela P, Dazzi F, De Angelis A, De Lotto B, Wilhelmi ED, Di Pierro F, Doert M, Dominguez A, Prester DD, Dorner D, Doro M, Einecke S, Glawion DE, Elsaesser D, Engelkemeier M, Ramazani VF, Fernandez-Barral A, Fidalgo D, Fonseca MV, Font L, Fruck C, Galindo D, Lopez RJG, Garczarczyk M, Gaug M, Giammaria P, Godinovic 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, Kuvezdic D, Lelas D, Lindfors E, Lombardi S, Longo F, Lopez M, Maggio C, Majumdar P, Makariev M, Maneva G, Manganaro M, Mannheim K, Maraschi L, Mariotti M, Martinez M, Mazin D, Menzel U, Minev M, Mirzoyan R, Moralejo A, Moreno V, Moretti E, Neustroev V, Niedzwiecki A, Rosillo MN, Nilsson K, Ninci D, Nishijima K, Noda K, Nogues L, Paiano S, Palacio J, Paneque D, Paoletti R, Paredes JM, Pedaletti G, Peresano M, Perri L, Persic M, Moroni PGP, Prandini E, Puljak I, Garcia JR, Reichardt I, Rhode W, Ribo M, Rico J, Righi C, Saito T, Satalecka K, Schroeder S, Schweizer T, Shore SN, Sitarek J, Snidaric I, Sobczynska D, Stamerra A, Strzys M, Suric T, Takalo L, Tavecchio F, Temnikov P, Terzic T, Tescaro D, Teshima M, Torres-Alba N, Treves A, Vanzo G, Acosta MV, Vovk I, Ward JE, Will M, Zaric D
Kustantaja: OXFORD UNIV PRESS
Kustannuspaikka: Oxford
Julkaisuvuosi: 2017
Journal: Monthly Notices of the Royal Astronomical Society
Tietokannassa oleva lehden nimi: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Lehden akronyymi: MON NOT R ASTRON SOC
Vuosikerta: 472
Numero: 3
Aloitussivu: 2956
Lopetussivu: 2962
Sivujen määrä: 7
ISSN: 0035-8711
eISSN: 1365-2966
DOI: https://doi.org/10.1093/mnras/stx2079
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 similar to 8 yr of Fermi-LAT to obtain the spectral shape between 60 MeV and 500 GeV. The spectra measured by the LAT andMAGIC telescopes are compatible within the errors and show a clear turn-off (4.6 sigma) 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 similar to 2.2 and an energy cut-off at similar to 10 TeV. This result indicates that Cas A is not contributing to the high energy (similar to 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 less than or similar to 180 mu G) like in the reverse shock.
