Theory and Phenomenology of Neutrinos in the Multimessenger Astronomy Era

This project is in the area of theoretical nuclear and particle astrophysics. It is centered on the physics of neutrinos, elementary particles that are produced abundantly in stars and galaxies. These astrophysical neutrinos have been observed on the ground, and many more observations are expected for the near future. Theoretical research will be very important to interpret the data. It will answer current open questions and pose new ones, on the fundamental processes that take place in stars and on how the properties of neutrinos influence them. The project will provide excellent training grounds for junior scientists that will prepare them for their future careers in industry and academia, thus enriching the scientific community. A major area of investigation is the physics of 1-10 MeV neutrinos from core collapse supernovae, which is a strategic opportunity for upcoming neutrino detectors. Part of the effort is to improve predictions of the diffuse flux of cosmological supernovae, which may soon be detected, by including realistic effects of stellar evolution on the collapsing star. Another goal is to study how the emission of neutrinos in a supernova can cause secondary signals of other messengers, like gamma ray flashes or gravitational waves. The interplay of neutrinos and gravitational wave emissions from a supernova is investigated, with focus on the potential of a joint analysis of data from these two messengers. A second thrust of the project is on interpreting the observed flux of TeV-PeV neutrinos from outside our galaxy, which is still of uncertain origin. The focus is a scenario, which is supported by recent data, where some of the detected neutrinos are produced by star-shredding black holes (tidal disruption events). The plan is to develop detailed, consistent predictions of neutrinos, photons and cosmic rays from these events, and compare the predictions to the existing data to constrain the main model parameters. This project advances the objectives of "Windows on the Universe: the Era of Multi-Messenger Astrophysics", one of the 10 Big Ideas for Future NSF Investments. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.