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Session 40 - Supernova Remnants & SN 1987A.
Display session, Thursday, January 08
Exhibit Hall,
We present evidence for the shock acceleration of cosmic ray electrons to TeV energies in the supernova remnant IC 443. We have analyzed spectroscopic x-ray and gamma-ray data from the ASCA, XTE, and CGRO missions. The ASCA data clearly indicate a nonthermal spectral component in the 2-10 keV energy band. Spatial analysis of these data shows that this emission is localized in two small regions of the remnant, one of which exhibits a very flat radio spectrum with index \lesssim 0.24. With XTE, we show that this nonthermal component extends up to at least 15 keV. It has been proposed that IC 443 is related to the unidentified EGRET source 2EG J0618+2234. This led us to analyze the archival EGRET data from this source as well as data from an observation of IC 443 made with the OSSE instrument on CGRO. The EGRET data can be well fit by a power- law with a photon index near 2. The OSSE observations yielded only upper limits but require that the spectrum of the EGRET source flattens between 1 MeV and 100 MeV. We combine these data with published radio and TeV gamma-ray data to produce a nonthermal multiwavelength spectrum for IC 443 which we fit with a cosmic ray interaction model. This model calculates the synchrotron, bremsstrahlung, inverse Compton, and neutral pion decay emission produced by locally accelerated cosmic rays interacting with ambient matter, soft photon fields, and magnetic fields. We find that by approximating the remnant as having two distinct spatial components, one with a flat radio spectrum where the nonthermal x-rays are produced and the other with a softer radio spectrum and no nonthermal x-rays, we can fit the nonthermal multiwavelength spectrum of IC 443.
