The Dark Matter Mystery

A substantial body of cosmological and astrophysical evidence points toward the existence of dark matter (DM) in our Universe. Nevertheless, the nature of this elusive component is still a mystery. This chapter is dedicated to an overview of the \(\Lambda \) CDM paradigm to explain particle dark matter. According to cosmological measurements, 24% of our Universe is constituted by non-baryonic DM. Adopting the DM paradigm can also explain measurements of astrophysical phenomena at the galactic scale. In this chapter, we first outline the pieces of evidence from astrophysics and cosmology for the existence of DM, and their potential issues at small scales with some alternatives. Then, we introduce widely motivated candidates to explain dark matter. We discuss the thermal freeze-out of Weakly Interacting Massive Particles DM and its expected thermal relic density together. Some existing bounds on particle dark matter models are also briefly discussed. We conclude the chapter by giving an overview of the nowadays available detection techniques that are deployed to shed light on the DM mystery.