© Jakob van den Eijnden

Massive stars, through their stellar winds and radiative output, are the power source of a wide range of highly energetic processes in the universe. Within our own galaxy, for instance, their radiative and mechanical feedback shapes their interstellar surroundings and parent stellar clusters. Excitingly, young stellar clusters that still contain a subset of their massive star population have been detected as sources of very-high-energy radiation in recent years, highlighting how these clusters may contribute to the acceleration of cosmic rays in the Milky Way. The energy budget for such acceleration, via stellar winds or supernova explosions, resides in the combined feedback of this massive stellar population. In this talk, I will discuss how we are using the current generation of SKA precursors telescopes to understand how these massive stars power particle acceleration. I will first discuss the specific case of stars that escaped their parent cluster and are travelling supersonically through the ISM, creating large-scale bow shocks. I will showcase the advancements that MeerKAT and ASKAP have allowed us to make in recent years — not only in finding radio counterparts of bow shocks, but also in characterising their non-thermal properties. I will then turn to how we plan to use radio survey data from SKA precursors, combined with multi-wavelength data from Gaia and IR surveys, to understand whether the conditions in and around stellar clusters are suitable for collective particle acceleration: the proposed mechanism to explain their very-high-energy emission and potential as sources of cosmic rays. Throughout, I will discuss the potential for these studies once the SKA is operational.