Observation of the W49B supernova remnant with Fermi-LAT and H.E.S.S.
Résumé
The supernova remnant (SNR) W49B originated from a core-collapse supernova that occurred few thousands years ago, and subsequently evolved into a mixed-morphology remnant, which is interacting with molecular clouds (MC). SNR/MC associations are particularly interesting for probing the acceleration of hadrons in SNRs and consequently the origin of Galactic cosmic rays. The molecular material in the vicinity of the source acts as an efficient target material for accelerated particles. These interactions can lead to gamma-ray emission, making SNR/MC a prime target for current gamma-ray observatories. W49B has been detected in gamma rays at high energies (HE, 0.1-100 GeV) and very high energies (VHE, >100 GeV) with the Fermi Large Area Telescope (Fermi-LAT) and the High Energy Stereoscopic System (H.E.S.S.), respectively. The latest results obtained on W49B with these instruments will be presented. In particular, the spectrum shows a break at low energies, similar to previous observations by the Fermi-LAT in other SNRs and interpreted as the signature of pion-decay gamma-ray emission. The implications of these results on the population of particles at the origin of the gamma-ray emission will be discussed.