Download or read book Hunting for Cosmic Neutrino Sources from Giga- to Exa-electronvolt with IceCube written by Alexander Pizzuto and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ever since the first observation of cosmic rays over a century ago, the origins of these high-energy particles have remained a mystery. Identifying and understanding the sources of these cosmic rays could provide invaluable insight into not only astrophysics but also fundamental particle physics. The IceCube Neutrino Observatory, a cubic-kilometer neutrino telescope, has made remarkable progress on this front -- first with the detection of a diffuse astrophysical neutrino flux in 2013, and later with the identification of a flaring blazar as a promising neutrino source. However, the sources of the vast majority of the diffuse neutrino flux remain unidentified. The goal of this thesis is to develop tools to identify astrophysical neutrino sources with current neutrino observatories. We show how analyzing neutrino data with new techniques could reveal an immense deal about the nature of the universe's most energetic particle accelerators. First, we describe a pipeline that uses realtime data to search for neutrino emission from astrophysical transients. Next, we look for neutrino emission in the direction of IceCube alert events to constrain populations of neutrino sources. We then present the first ever search for sub-TeV neutrino emission from novae. Lastly, we search for neutrino emission coincident with ANITA neutrino candidates, and show how IceCube can search for neutrinos with energies traditionally reserved for radio neutrino detectors. All of the analyses resulted in non-detections, and we present upper-limits for each. Our results include, but are not limited to, (1) the first constraints on neutrino emission from novae, (2) the first constraints on neutrino emission from fast radio bursts at a level more constraining than the diffuse astrophysical neutrino flux, (3) the first constraints on populations of day-scale transient neutrino sources, and (4) the first joint interpretation of very-high-energy optical Cherenkov neutrino data and ultra-high-energy radio neutrino data in the context of astrophysical neutrino sources. Although all of these analyses resulted in non-detections, these tools have already provided interesting constraints on the sources of high-energy neutrinos, and we are hopeful that the tools presented here will assist with the identification of cosmic neutrino sources in the years to come.