Detection prospects for Axion-Like Particles (ALP) Searches with the Southern Wide-Field Gamma-ray Observatory (SWGO)

It is known that the detection of VHE gamma rays emitted by extragalactic sources such as AGNs is very challenging due to steeply falling fluxes of photon spectra and the absorption of photons in extragalactic background light (EBL) which pervade the Universe. This attenuation due to EBL is dominant at higher energies (above ∼ 300 GeV). In the presence of ambient magnetic fields including the AGN jet magnetic field, intra-cluster magnetic fields (ICMF), inter-galactic magnetic fields (IGMF) and the magnetic field of Milky-way, gamma rays can be converted to hypothetical Dark Matter candidates ALPs and vice versa through energy dependent oscillations. ALPs can travel through regions which are opaque to gamma rays due to the presence of background photon fields. As a result of ALP-photon mixing, excess in gamma ray flux can be observed in the spectrum at very high energies that can be detected with future instruments on Earth such as Cherenkov Telescope Array CTA and SWGO. The aim of the thesis is to test the sensitivity performance of proposed SWGO and anticipate how many GeV sources can be detected by SWGO if ALP-photon conversion occurs. The study also explores the constraints on the parameter space (mass and coupling) of ALPs.