CAREER: WoU-MMA: Understanding the Neutrino Sky

Cosmic rays, particles arriving at the Earth from distant sources, can have energies exceeding 10 million times that of the highest-energy man-made particle accelerators. A century after their discovery, however, the origin of these remarkable particles, and the process responsible for giving them these energies remains unknown. A first glimpse at these sources has come over the last decade from the Antarctic's IceCube Neutrino Observatory, revealing the approximate locations of a number of them, but without the precision to identify what they are. This award supports new approaches to analyze existing IceCube data to untangle this mystery as well as the first steps to develop a next-generation observatory, P-ONE, at the bottom of the Pacific Ocean off the Washington coast that will provide much higher-precision measurements and fully open the new window on the universe provided by IceCube -- as well as providing a unique platform for studying the deep ocean. As part of this effort, the award will also support work to improve teaching in physics to improve accessibility and emphasize the subject as an experimental science rather than as only a mathematical exercise and to better align coursework with the skills needed for both academic and industry careers. Neutrinos, able to pass through obstacles opaque to light, provide a unique view of the high-energy and distant universe. Over the last eight years, the IceCube Neutrino Observatory has provided the first glimpse of these high-energy neutrinos from astrophysical objects, with the first detection of a bright, diffuse background (2014) and of the first source (2018). These results present something of a puzzle: The neutrino sky is more isotropic than light at any wavelength except the cosmic microwave background and the first (and presumably brightest) source is both a vast distance from Earth and otherwise unremarkable. Together, these observations strongly suggest that neutrinos are telling us something fundamentally new about the universe, something that we have not anticipated and have no other way to see, but we do yet have the data to understand what it might be. This award approaches this problem on two paths: new methods for analysis of existing IceCube data, notably by cross-correlation with millimeter-band observations of active galaxies, of which hints have been reported, and by development of the electronics for a new neutrino telescope in the northeast Pacific, P-ONE. P-ONE is expected to achieve angular resolution 4-5 times better than IceCube, increasing the expected number of detected sources by an order of magnitude and allowing the first population studies of neutrino sources. Moreover, P-ONE's peak sensitivity will be in the southern sky, unlike IceCube, which makes it well-matched to studies of our galaxy and the fields of view of most next-generation electromagnetic observatories (Rubin, ELT, CMB-S4, SKA, SWGO, etc.). Anticipated education and outreach aspects of the award include outreach in Michigan schools, supporting the undergraduate to graduate transition, and new programs for teaching experimental physics at the graduate and undergraduate level. In addition, the award supports the installation of a new exhibit on cosmic rays and particle physics at the Impression Five science center, a major center for science education in mid-Michigan attracting nearly 200,000 visitors a year. The award is aligned with the NSF Big Idea of Windows on the Universe: the Era of Multi-messenger Astrophysics as it coordinates the use of multi-messengers observations utilizing long wavelength (mm/cm) photons with high energy neutrinos from IceCube and will improve the interpretation of data especially through improving the understanding of diffuse sources. 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.