Ponente
Descripción
In recent years, massive star cluster environments have emerged as a new class of gamma-ray sources capable of accelerating particles to very-high energies, to such extent that they could complement the supernova model for the origin of galactic cosmic rays. The environment sculpted by the interaction of powerful stellar winds is complex, highly structured from small (pc) to large (100 pc) scales, and presents a priori a number of plausible particle acceleration sites. Theoretical modelling is key to pinpoint the origin of the emission and constrain acceleration scenarios which could be probed with the next generation of gamma-ray instruments.
The feedback of massive stars onto their environment is driven by non-trivial wind interactions which are inherently three-dimensional, making simple analytic models unable to fully capture the shock dynamics or to predict the properties of the magnetic fields. Understanding non-thermal phenomena in star-forming environments therefore requires detailed large-scale magnetohydrodynamic simulations. In this talk I present a novel method to simulate massive star cluster winds of arbitrary age in a variety of configurations. I will highlight the conditions required to generate a large-scale wind termination shock which could efficiently accelerate particles above hundreds of TeV. It is found that only compact clusters hosting a large number of powerful stars can become ultra-high energy (>100 TeV) sources after several million years of evolution. This result supports the wind termination shock scenario for Westerlund 1, but disproves this possibility in the case of the Cygnus region.
