This award funds the research activities of Professor Kohta Murase at the Pennsylvania State University.
A new frontier in particle astrophysics has just opened up with the recent discovery of high-energy extra-terrestrial neutrinos by the the Gigaton-scale neutrino detector known as IceCube. Neutrinos are ghostlike neutral particles which can escape from dense regions in the Universe; because they interact so weakly with other forms of matter, they arrive undeflected at Earth and thus tend to point directly back to the distant astrophysical sources that produced them. The origin of these high-energy neutrinos recently discovered by IceCube is a new mystery in the field, and solving this problem would allow us not only to understand the microphysics and mechanisms of the sources but also to obtain important clues about an old mystery, the origin of cosmic rays. More general, this discovery allows us to utilize neutrinos as probes of neutrino properties, dark matter, and other forms of fundamental physics. A major goal of Professor Murase's research is to address these new and old problems through combinations of data coming not only from neutrinos but also from gamma rays, through theoretical calculations of particle production and propagation. This research is interdisciplinary, including topics in astrophysics and particle physics and connecting theoretical ideas directly to experimental and observational data. As a result, this research will advance the national interest by promoting the progress of fundamental science. This project is also envisioned to have significant broader impacts. It will involve and thereby provide training to graduate students involved in this research, and key concepts of particle astrophysics will be disseminated among educators at high schools and community colleges.
More technically, one of the key ingredients in this research is the strategic multi-messenger approach in which predictions for different astroparticles (neutrinos, gamma rays, and cosmic rays) are confronted with data. With sophisticated calculations including all relevant microphysical processes, the PI will test various models for the astroparticle origins and extract fundamental insights into the source physics of extreme astrophysical objects. The multi-messenger connection among the measured neutrino, gamma-ray, and cosmic-ray backgrounds will be examined, and source classes of cosmic-ray accelerators that cannot be directly probed by gamma rays will also be studied. The results of this study should be useful for the design of proposed next-generation neutrino and gamma-ray detectors.
