TeV gamma-ray Observations of the Supernova Remnant RCW86 with the CANGAROO-II telescope

The supernova remnant RCW86 (G315.4-2.3) has been observed with the CANGAROO-II 10 m telescope from Woomera, South Australia. ASCA detected non-thermal X-ray emission from the south-west shell of RCW86, which is brighter than that from SN1006. The multiwavelength spectrum of RCW86 derived from radio and X-ray data indicates that the emission is due to the synchrotron radiation, and it is argued that high energy electrons emitting the detected synchrotron radiation are expected to be accelerated up to 20 TeV. Therefore, the radiation due to inverse Compton scattering with the photons of the 2.7 K cosmic microwave background is also expected to be detectable with the CANGAROO-II telescope if the magnetic field is as weak as that of SN1006. We observed RCW86 in 2001 and 2002 for a total observation time of 79 hours for ON-source data. The detection energy threshold was estimated from Monte Carlo simulations to be around 1 TeV.