Condensed Matter Physics, 1998, vol. 1, No. 3, p. 655-667, English

Authors:B.Hnatyk, O.Petruk (Pidstryhach Institute for Applied Problems in Mechanics & Mathematics National Academy of Sciences of Ukraine, 3$^M-!$ Naukova St., UA-290601 Lviv, Ukraine)

We examine the hypothesis that some supernova remnants (SNRs) may be responsible for some unidentified $\gamma$-ray sources detected by EGRET instrument aboard the Compton Gamma Ray Observatory. If this is the case, $\gamma$-rays are produced via pion production and decay from direct inelastic collisions of accelerated by SNR shock wave ultrarelativistic protons with target protons of the interstellar medium. We develop a 3-D hydrodynamical model of SNR IC 443 as a possible cosmic $\gamma$-ray source 2EG J0618+2234. The derived parameters of IC 443: the explosion energy $E_o=2.7\cdot 10^{50}$ erg, the initial hydrogen number density $n(0)=0.21$ cm$^{-3}$, the mean radius $\overline{R}=9.6$ pc and the age $t=4500$ yr result in too low $\gamma$-ray flux, mainly because of the low explosion energy. Therefore, we investigate in detail the hydrodynamics of IC 443 interaction with a nearby massive molecular cloud and show that the reverse shock wave considerably increases the cosmic ray density in the interaction region. Meantime, the Rayleigh-Taylor instability of contact discontinuity between the SNR and the cloud provides an effective mixing of the containing cosmic ray plasma and the cloud material. We show that the resulting $\gamma$-ray flux is consistent with the observational data.

Key words: supernova remnants, individual: IC 443, X-rays, cosmic rays, \gamma -rays
Comments: Figs. 3, Refs. 24, Tabs. 0.

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