Observation of Supernova Remnant IC 443 with the Fermi Large Area Telescope

We report observation of the supernova remnant (SNR) IC 443 (G189.1+3.0) with the Fermi Gamma-ray Space Telescope Large Area Telescope (LAT) in the energy band between 200 MeV and 50 GeV. IC 443 is a shell-type SNR with mixed morphology located off the outer Galactic plane where high-energy emission has been detected in the X-ray, GeV and TeV gamma-ray bands. Past observations suggest IC 443 has been interacting with surrounding interstellar matter. Proximity between dense shocked molecular clouds and GeV-TeV gamma-ray emission regions detected by EGRET, MAGIC, and VERITAS suggests an interpretation that cosmic-ray (CR) particles are accelerated by the SNR. With the high gamma-ray statistics and broad energy coverage provided by the LAT, we accurately characterize the gamma-ray emission produced by the CRs accelerated at IC 443. The emission region is extended in the energy band with θ68 = 0fdg27 ± 0fdg01(stat) ± 0fdg03(sys) for an assumed two-dimensional Gaussian profile and overlaps almost completely with the extended source region of VERITAS. Its centroid is displaced significantly from the known pulsar wind nebula (PWN) which suggests the PWN is not the major contributor in the present energy band. The observed spectrum changes its power-law slope continuously and continues smoothly to the MAGIC and VERITAS data points. The combined gamma-ray spectrum (200 MeV <E< 2 TeV) is reproduced well by decays of neutral pions produced by a broken power-law proton spectrum with a break around 70 GeV.Fil: Abdo, A. A.. Spece Sciences División. Naval Research Laboratory; Estados Unidos. National Academy of Sciences; Estados UnidosFil: Ackermann, M.. University Of Stanford; Estados UnidosFil: Ajello, M.. University Of Stanford; Estados UnidosFil: Baldini, L.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Ballet, J.. Universite Paris Diderot; FranciaFil: Barbiellini, G.. Universita di Trieste; ItaliaFil: Bastieri, D.. Universita Di Padova; ItaliaFil: Baughman, B. M.. Ohio State University; Estados UnidosFil: Bechtol, K.. University Of Stanford; Estados UnidosFil: Bellazzini, R.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Berenji, B.. University Of Stanford; Estados UnidosFil: Blandford, R. D.. University Of Stanford; Estados UnidosFil: Bloom, E. D.. University Of Stanford; Estados UnidosFil: Bonamente, E.. Universita degli Studi di Perugia; ItaliaFil: Borgland, A. W.. University Of Stanford; Estados UnidosFil: Bregeon, J.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Brez, A.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Brigida, M.. Universita e del Politecnico di Bari; ItaliaFil: Bruel, P.. Ecole Polytechnique; FranciaFil: Burnett, T. H.. University of Washington; Estados UnidosFil: Buson, S.. Universita Di Padova; ItaliaFil: Caliandro, G. A.. Universita e del Politecnico di Bari; ItaliaFil: Cameron, R. A.. University Of Stanford; Estados UnidosFil: Caraveo, P. A.. Istituto di Astrofisica Spaziale e Fisica Cosmica; ItaliaFil: Casandjian, J. M.. Université Paris Diderot - Paris 7; FranciaFil: Cecchi, C.. Universita degli Studi di Perugia; ItaliaFil: Celik, O.. National Aeronautics And Space Administration. Goddart Institute For Space Studies; Estados UnidosFil: Chekhtman, A..  Space Science Division; Estados UnidosFil: Cheung, C. C.. National Aeronautics And Space Administration. Goddart Institute For Space Studies; Estados UnidosFil: Chiang, J.. University Of Stanford; Estados UnidosFil: Cillis, Analia Nilda. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Fermi-LAT Collaboration