Federica Pompa (University of Valencia)
"Galactic Cataclysm: Supernova neutronization burst to constraint neutrino mass"
Supernova (SN) explosions are the most powerful cosmic factories of all flavors, MeV-scale, neutrinos. Their detection is of great importance not only for astrophysics, but also to shed light on neutrino properties. Since the first observation of a SN neutrino signal in the 1987, the international network of SN neutrinos observatories has been greatly expanded, in order to detect the next galactic SN explosion with much higher statistics and accuracy in the neutrino energy-time-flavor space. In this contribution, I will discuss the constraints that we expect to achieve with next-generation neutrino experiments like DUNE and Hyper-Kamiokande, on the absolute value of the neutrino mass, obtained by considering the time delay in the propagation of massive neutrinos from production in the SN environment to their detection. Furthermore, the comparison of sensitivities achieved for the two possible neutrino mass orderings is discussed, as well as the effects due to propagation in the Earth matter.
Speaker: Jorge Terol-Calvo (Institute of Astrophysics of the Canary Islands)
"Cosmology Safe Large Neutrino Masses"
Cosmological constraints on the sum of neutrino masses can be relaxed by considering a scenario where the number density of active neutrinos is reduced, while the effective number of neutrino species is maintained by introducing a new component of dark radiation. In this talk, I'll present a UV model based on a U(1) symmetry in the dark sector, which can be either gauged or global, to realize this intriguing concept. The model employs the seesaw mechanism to generate neutrino masses and introduces O(10) generations of massless sterile neutrinos that contribute to the dark radiation component. This framework allows for accommodating active neutrino masses in the range of electron volts (eV), which aligns with the sensitivity range of the KATRIN experiment. We further discuss the phenomenology of the model and identify the parameter space that satisfies the constraints imposed by current observations. Our study sheds light on the interplay between neutrino masses, dark radiation, and the underlying U(1) symmetry in the dark sector, providing insights into the fundamental properties of neutrinos and their cosmological implications.