Discovery of TeV γ-ray emission from the neighbourhood of the supernova remnant G24.7+0.6 by MAGIC

Acciari, V. A.; Ansoldi, S.; Antonelli, L. A.; Arbet Engels, A.; Arcaro, C.; Baack, D.; Babic, A.; Banerjee, B.; Bangale, P.; De Almeida, U. B.; Barrio, J. A.; Becerra Gonzalez, J.; Bednarek, W.; Bernardini, E.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.; Biland, A.; Blanch, O.; Bonnoli, G.; Carosi, R.; Ceribella, G.; Chatterjee, A.; Colak, S. M.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Cumani, P.; D'Elia, V.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; Delfino, M.; Delgado, J.; Di Pierro, F.; Dominguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Elsaesser, D.; Fallah Ramazani, V.; Fattorini, A.; Fernandez-Barral, A.; Ferrara, G.; Fidalgo, D.; Foffano, L.; Fonseca, M. V.; Font, L.; Fruck, C.; Galindo, D.; Gallozzi, S.; Garcia Lopez, R. J.; Garczarczyk, M.; Gaug, M.; Giammaria, P.; Godinovic, N.; Guberman, D.; Hadasch, D.; Hahn, A.; Hassan, T.; Herrera, J.; Hoang, J.; Hrupec, D.; Inoue, S.; Ishio, K.; Iwamura, Y.; Kubo, H.; Kushida, J.; Kuvezdic, D.; Lamastra, A.; Lelas, D.; Leone, F.; Lindfors, E.; Lombardi, S.; Longo, F.; Lopez, M.; Lopez-Oramas, A.; Maggio, C.; Majumdar, P.; Makariev, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martinez, M.; Masuda, S.; Mazin, D.; Minev, M.; Miranda, J. M.; Mirzoyan, R.; Molina, E.; Moralejo, A.; Moreno, V.; Moretti, E.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nigro, C.; Nilsson, K.; Ninci, D.; Nishijima, K.; Noda, K.; Nogues, L.; Paiano, S.; Palacio, J.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Pedaletti, G.; Penil, P.; Peresano, M.; Persic, M.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Garcia, J. R.; Rhode, W.; Ribo, M.; Rico, J.; Righi, C.; Rugliancich, A.; Saha, L.; Saito, T.; Satalecka, K.; Schweizer, T.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Somero, A.; Stamerra, A.; Strzys, M.; Suric, T.; Tavecchio, F.; Temnikov, P.; Terzic, T.; Teshima, M.; Torres-Alba, N.; Tsujimoto, S.; Vanzo, G.; Vazquez Acosta, M.; Vovk, I.; Ward, J. E.; Will, M.; Zaric, D.; De Ona Wilhelmi, E.; Torres, D. F.; Zanin, R.

doi:10.1093/mnras/sty3387

SNR G24.7+0.6 is a 9.5 kyrs radio and γ-ray supernova remnant evolving in a dense medium. In the GeV regime, SNR G24.7+0.6 (3FHL J1834.1-0706e/FGES J1834.1-0706) shows a hard spectral index (T ~ 2) up to 200 GeV, which makes it a good candidate to be observed with Cherenkov telescopes such as MAGIC. We observed the field of view of SNR G24.7+0.6 with the MAGIC telescopes for a total of 31 h. We detect very high-energy γ-ray emission from an extended source located 0.34° away from the centre of the radio SNR. The new source, named MAGIC J1835-069 is detected up to 5 TeV, and its spectrum is well-represented by a power-law function with spectral index of 2.74 ± 0.08. The complexity of the region makes the identification of the origin of the very high-energy emission difficult; however, the spectral agreement with the LAT source and overlapping position at less than 1.5σ point to a common origin. We analysed 8 yr of Fermi-LAT data to extend the spectrum of the source down to 60 MeV. Fermi-LAT and MAGIC spectra overlap within errors and the global broad-band spectrum is described by a power law with exponential cut-off at 1.9 ± 0.5 TeV. The detected γ-ray emission can be interpreted as the results of proton-proton interaction between the supernova and the CO-rich surrounding.