Title: Towards a 5-sigma detection on the sum of the neutrino masses

Abstract: I will briefly show how the observation of neutrino oscillations have pointed out that neutrinos have masses, showing the existence of physics beyond the standard model. Determining the neutrino masses and their hierarchy are among the most important goals of modern physics. I will discuss how we can provide answers to these fundamental questions via cosmological observations. I will first present one of the predictions of the Big Bang theory: the existence of a cosmic neutrino background. I will then explain why cosmic neutrinos leave unique signatures on cosmological observables, and how we can use them to constrain the neutrino masses with a very high confidence level. I will present preliminary results from the Quijote simulations, a large suite of 23000 N-body simulations containing at a single redshift more than 3.3 trillions of particles. Next, I will discuss the theoretical challenges we will need to surpass to extract the maximum cosmological and astrophysical information from upcoming surveys, and how we can use machine learning to tackle them.