In view of the discovery of HESS J1023-575 (discussed in a separate presentation), we examine other very high energy (VHE) gamma-ray sources possibly associated with massive star clusters. Particle acceleration in massive star forming regions can proceed at the interface of two interacting winds or result from a collective process; multiple shock acceleration or MHD turbulence. The gamma-ray emission can either take place in the shell at the edge of the superbubble blown by the winds and multiple supernova explosions. Non-thermal radiation from the shell structure then trace the interaction of energetic particles (ions and/or electrons) with the surrounding interstellar matter. In particular, HESS J1837-069 is spatially coincident with a recently discovered very massive star cluster. We discuss the VHE gamma-ray data resulting from H.E.S.S. observations on this or other possible such associations. We consider data in other wavelength domains, in particular in X-rays, and examine the available evidence that the VHE emission could originate in particles accelerated by the above-mentioned mechanisms in massive star clusters.

HESS collaboration

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 2 (OG part 1), pages 787-790