Astroparticle Physics: Neutrinos and Dark Matter

This lecture discusses the role of neutrinos in astroparticle physics and their potential as dark matter candidates. It begins with a recap of the previous lecture on the dynamics of the universe, emphasizing critical density and dark matter. The instructor introduces the concept of the cosmological neutrino background and explores the thermal history of the universe. The lecture delves into weakly interacting massive particles (WIMPs) and their significance in the context of dark matter. The instructor explains how neutrinos interact through weak interactions and discusses their mean free path and interaction time scales. The discussion extends to dark matter in galaxy clusters, highlighting the application of the virial theorem to estimate mass in clusters. Observations of hot gas in these clusters provide evidence for dark matter's presence. The lecture concludes with an analysis of the Milky Way's rotation curve, illustrating how dark matter influences galaxy dynamics and the challenges in detecting it through indirect methods such as gravitational lensing.