An updated view of the VHE gamma-ray sky around the stellar cluster Westerlund 2 with the H.E.S.S. experiment

Résumé fourni par la source

Since the last H.E.S.S. publication on the stellar cluster Westerlund 2 in 2011, the H.E.S.S. dataset on this region has increased more than three-fold in exposure to $\sim220\,$h of total observation time. By applying a novel approach to correct for atmospheric variations in IACT data, the commonly applied data quality selection criteria can be adapted to exploit as much of this dataset as possible. In combination with current analysis techniques, it is furthermore possible to disentangle and better characterise this complex region of the gamma-ray sky. Applying an extensive 3D fitting procedure, we find three distinct VHE gamma-ray sources in the vicinity of Westerlund 2, adding a new emission region to the previously reported sources HESS J1023$-$575 and HESS~J1026$-$582. Even though the sources partly overlap, their spectral indices differ from one another, providing new clues on the relativistic particle acceleration and propagation in the region around the massive star cluster. The new source component shows an elongated morphology that seems to emerge from the star cluster, following the multi-parsec-scale CO jet cloud initially found in NANTEN data as reported in 2009.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.