Speaker
Description
The Transient High-Energy Sky and Early Universe Surveyor (THESEUS) will provide new opportunities for time-domain studies of young stellar objects through its soft X-ray, hard X-ray/γ-ray, and near-infrared capabilities. We investigate the potential of coordinated multi-wavelength observations of Galactic star-forming regions, with emphasis on X-ray flares, ultraviolet followup, and the most energetic megaflare events. Since predicted flare yields alone do not fully characterize the suitability of different regions for coordinated observations, we introduce a simple comparative metric that combines flare yield with source distance. The resulting ranking favours nearby star-forming regions for detailed multi-wavelength studies, while distant massive complexes remain valuable for statistical investigations of rare energetic events. We also present an order-of-magnitude estimate of the prospects for detecting gamma-ray megaflares with THESEUS/XGIS based on published Fermi-LAT results, illustrating how source distance and stellar population together influence the expected scientific return of high-energy observations.