Very high energy gamma rays from the composite SNR G 0.9+0.1

Very high energy (> 100 GeV) gamma-ray emission has been detected for the first time from the composite supernova remnant G0.9+0.1 using the H.E.S.S. instrument. The source is detected with a significance of 13 sigma, and a photon flux above 200 GeV of (5.7+/-0.7 stat +/- 1.2 sys) * 10^-12 cm^-2 s^-1, making it one of the weakest sources ever detected at TeV energies. The photon spectrum is compatible with a power law (dN/dE \propto E^-Gamma) with photon index Gamma = 2.40 +/- 0.11 stat +/- 0.20 sys. The gamma-ray emission appears to originate in the plerionic core of the remnant, rather than the shell, and can be plausibly explained as inverse Compton scattering of relativistic electrons.