HESS J1023-575: Non-thermal particle acceleration associated with the young stellar cluster Westerlund 2

TL;DR

H.E.S.S. observations reveal very-high-energy gamma-ray emission from Westerlund 2, indicating particle acceleration processes in this young stellar cluster, with multiple possible emission mechanisms discussed.

Contribution

First detection of VHE gamma-ray emission from Westerlund 2, providing evidence for particle acceleration in a young stellar cluster environment.

Findings

Detection of gamma-ray emission associated with Westerlund 2

Multiple emission scenarios considered and compared

Insights into particle acceleration mechanisms in stellar clusters

Abstract

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.