Study of the very high energy emission from star-forming regions and young massive star clusters

Cosmic rays (CRs) are a fundamental component of the Cosmos. They can penetrate and ionise the dense gas core of molecular clouds, affecting the dynamics of the cloud itself and triggering chemical reactions that lead to the creation of complex molecular compounds. In star-forming complexes, CRs can be accelerated by the wind of newly born massive stars, often found in young massive stellar clusters (YMSC). The amount of freshly injected CRs can be probed by the observations of high-energy and very-high-energy gamma-rays. In this regard, the future Cherenkov Telescope Array Observatory (CTAO) will play a crucial role. CTAO will be composed of around 100 telescopes deployed on two sites, one in Northern and one in the Southern Hemisphere. The arrays will cover a wide energy range from tens of GeV to hundreds of TeV employing telescopes of three sizes: the Large, Medium and Small Sized Telescopes with 23 m, 14 m and 4.5 m mirror diameters, respectively. Each telescope is optimized for the detection of photons below 1 TeV (LST), between 1-10 TeV (MST) and above 10 TeV (SST). The first LST prototype, LST-1, is currently ending its commissioning phase and is starting to collect scientific data. During the present observational cycle, two observational proposals on YMSC were submitted for the very first time. These observations are challenging due to the extension of the expected gamma-ray emission from YMSC and to the limited Field of View (FoV) of the Cherenkov telescopes (around 2.3° radius for LST-1). In this context is of paramount importance to optimise the reconstruction analysis chain (currently under development) for extended sources and to rank the best targets for the next observational campaigns both of LST-1 and of the upcoming 3 LSTs currently under construction at the CTAO-Northern site.