The results from H.E.S.S. observations towards Westerlund 2 are presented. The detection of very-high-energy gamma-ray emission towards the young stellar cluster Westerlund 2 in the HII complex RCW49 by H.E.S.S. provides ample evidence that particle
acceleration to extreme energies is associated with this region. A variety of possible emission scenarios is mentioned, ranging from high-energy gamma-ray production in the colliding wind zone of the massive Wolf-Rayet binary WR20a, collective wind scenarios, diffusive shock acceleration at the boundaries of wind-blown bubbles in the stellar cluster, and outbreak phenomena from hot stellar winds into the interstellar medium. These scenarios are briefly compared to the characteristics of the associated new VHE gamma-ray source HESS J1023-575, and conclusions on the validity of the respective emission scenarios for high-energy gamma-ray production in the Westerlund 2 system are drawn.
In the very-high-energy (VHE) gamma-ray wave band, pulsar wind nebulae (PWNe) represent to date the most populous class of Galactic sources. Nevertheless, the details of the energy conversion mechanisms in the vicinity of pulsars are not well underst
ood, nor is it known which pulsars are able to drive PWNe and emit high-energy radiation. In this paper we present a systematic study of a connection between pulsars and VHE gamma-ray sources based on a deep survey of the inner Galactic plane conducted with the High Energy Stereoscopic System (H.E.S.S.). We find clear evidence that pulsars with large spin-down energy flux are associated with VHE gamma-ray sources. This implies that these pulsars emit on the order of 1% of their spin-down energy as TeV gamma-rays.
