Expected performances of the SWGO observatory to ultra high energy gamma-ray

The Southern Wide-field Gamma-ray Observatory (SWGO) will be a next generation ground array experiment probing the Southern sky in search of gamma-ray sources from the Galactic plane. The experiment will be located in the Atacama Astronomical Park at 4770 m above sea level. The observatory will be a wide field of view and high duty cycle (almost 100%) array measuring the Extensive Air Showers (EAS) generated by primaries of energy greater than 100 GeV. SWGO will rely on the Water Cherenkov Detector (WCD) technique to study the ground particle distribution of the secondary particles of the EAS, to reconstruct the characteristics of the primary gamma rays. Recently, the HAWC and LHAASO experiments detected various sources at energies greater than 100 TeV, both arrays being in the Northern hemisphere, and there is a clear lack of an observatory exploring the Southern hemisphere sky at these energies. In this contribution, we describe the expected performance of the current reference configuration (nearly 1 𝑘𝑚^2 area with a dense core at the centre) of the SWGO observatory in the 30 TeV - 1 PeV energy range. The energy resolution is about 15% and the angular one is 0.1-0.15 degrees, showing an improvement with respect to current observatories. Gamma-hadron separation power and sensitivity are expected to be at least comparable with LHAASO and further studies with improved simulations will allow to refine the performance quantities.