2000A&A...354L..57M

We report the results of TeV gamma-ray observations of the shell type SNR RX J1713.7-3946 (G347.3-0.5). The discovery of strong non-thermal X-ray emission from the northwest part of the remnant strongly suggests the existence of electrons with energies up to ∼100TeV in the remnant, making the SNR a good candidate TeV gamma-ray source. We observed RX J1713.7-3946 from May to August 1998 with the CANGAROO 3.8m atmospheric imaging Cerenkov telescope and obtained evidence for TeV gamma-ray emission from the NW rim of the remnant with the significance of ∼5.6σ. The observed TeV gamma-ray flux from the NW rim region was estimated to be (5.3±0.9[statistical]±1.6[systematic])x10^–12photons/cm²/s at energies ≥1.8±0.9TeV. The data indicate that the emitting region is much broader than the point spread function of our telescope. The extent of the emission is consistent with that of hard X-rays observed by ASCA. This TeV gamma-ray emission can be attributed to the Inverse Compton scattering of the Cosmic Microwave Background Radiation by shock accelerated ultra-relativistic electrons. Under this assumption, a rather low magnetic field of ∼11µG is deduced for the remnant from our observation.