Data di Pubblicazione:
2013
Abstract:
Cosmic rays are particles (mostly protons) accelerated to relativistic speeds. Despite wide agreement
that supernova remnants (SNRs) are the sources of galactic cosmic rays, unequivocal evidence for the
acceleration of protons in these objects is still lacking. When accelerated protons encounter interstellar
material, they produce neutral pions, which in turn decay into gamma rays. This offers a compelling way
to detect the acceleration sites of protons. The identification of pion-decay gamma rays has been difficult
because high-energy electrons also produce gamma rays via bremsstrahlung and inverse Compton
scattering. We detected the characteristic pion-decay feature in the gamma-ray spectra of two SNRs, IC 443
and W44, with the Fermi Large Area Telescope. This detection provides direct evidence that cosmic-ray
protons are accelerated in SNRs.
Tipologia CRIS:
03A-Articolo su Rivista
Elenco autori:
M. Ackermann;M. Ajello;A. Allafort;L. Baldini;J. Ballet;G. Barbiellini;M. G. Baring;D. Bastieri;K. Bechtol;R. Bellazzini;R. D. Blandford;E. D. Bloom;E. Bonamente;A. W. Borgland;E. Bottacini;T. J. Brandt;J. Bregeon;M. Brigida;P. Bruel;R. Buehler;G. Busetto;S. Buson;G. A. Caliandro;R. A. Cameron;P. A. Caraveo;J. M. Casandjian;C. Cecchi;O. Celik;E. Charles;S. Chaty;R. C. G. Chaves;A. Chekhtman;C. C. Cheung;J. Chiang;G. Chiaro;A. N. Cillis;S. Ciprini;R. Claus;J. Cohen-Tanugi;L. R. Cominsky;J. Conrad;S. Corbel;S. Cutini;F. D'Ammando;A. de Angelis;F. de Palma;C. D. Dermer;E. do Couto e Silva;P. S. Drell;A. Drlica-Wagner;L. Falletti;C. Favuzzi;E. C. Ferrara;A. Franckowiak;Y. Fukazawa;S. Funk;P. Fusco;F. Gargano;S. Germani;N. Giglietto;P. Giommi;F. Giordano;M. Giroletti;T. Glanzman;G. Godfrey;I. A. Grenier;M.- H. Grondin;J. E. Grove;S. Guiriec;D. Hadasch;Y. Hanabata;A. K. Harding;M. Hayashida;K. Hayashi;E. Hays;J. W. Hewitt;A. B. Hill;R. E. Hughes;M. S. Jackson;T. Jogler;G. Johannesson;A. S. Johnson;T. Kamae;J. Kataoka;J. Katsuta;J. Knodlseder;M. Kuss;J. Lande;S. Larsson;L. Latronico;M. Lemoine-Goumard;F. Longo;F. Loparco;M. N. Lovellette;P. Lubrano;G. M. Madejski;F. Massaro;M. Mayer;M. N. Mazziotta;J. E. McEnery;J. Mehault;P. F. Michelson;R. P. Mignani;W. Mitthumsiri;T. Mizuno;A. A. Moiseev;M. E. Monzani;A. Morselli;I. V. Moskalenko;S. Murgia;T. Nakamori;R. Nemmen;E. Nuss;M. Ohno;T. Ohsugi;N. Omodei;M. Orienti;E. Orlando;J. F. Ormes;D. Paneque;J. S. Perkins;M. Pesce-Rollins;F. Piron;G. Pivato;S. Raino;R. Rando;M. Razzano;S. Razzaque;A. Reimer;O. Reimer;S. Ritz;C. Romoli;M. Sanchez-Conde;A. Schulz;C. Sgro;P. E. Simeon;E. J. Siskind;D. A. Smith;G. Spandre;P. Spinelli;F. W. Stecker;A. W. Strong;D. J. Suson;H. Tajima;H. Takahashi;T. Takahashi;T. Tanaka;J. G. Thayer;J. B. Thayer;D. J. Thompson;S. E. Thorsett;L. Tibaldo;O. Tibolla;M. Tinivella;E. Troja;Y. Uchiyama;T. L. Usher;J. Vandenbroucke;V. Vasileiou;G. Vianello;V. Vitale;A. P. Waite;M. Werner;B. L. Winer;K. S. Wood;M. Wood;R. Yamazaki;Z. Yang;S. Zimmer
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