H.E.S.S. observations of the supernova remnant RX J0852.0-4622 : shell-type morphology and spectrum of a widely extended very high energy gamma-ray source

The shell-type supernova remnant RX J0852.0-4622 was observed with the High Energy Stereoscopic System (H.E.S.S.) of atmospheric Cerenkov telescopes between 2004 December and 2005 May for a total observation time of 33 hr, above an average gamma-ray energy threshold of 250 GeV. The angular resolution of ~0.06° (for events triggering three or four telescopes) and the large field of view of H.E.S.S. (5° diameter) are well adapted to studying the morphology of the object in very high energy gamma rays, which exhibits a remarkably thin shell very similar to the features observed in the radio range and in X-rays. The spectral analysis of the source from 300 GeV to 20 TeV is also presented. Finally, the possible origins of the very high energy gamma-ray emission (inverse Compton scattering by electrons or the decay of neutral pions produced by proton interactions) are discussed, on the basis of morphological and spectral features obtained at different wavelengths.