Vieregg studies ultrahigh-energy neutrinos — neutrinos with energies of more than 10 electronvolts — that originate from beyond the Milky Way galaxy, shedding light on the nature of neutrinos and helping to home in on extragalactic sources of the particle. Vieregg is involved in a number of cosmic-neutrino experiments, including the balloon-borne ANITA experiment and the Askaryan Radio Array experiment, which uses detectors buried in the Antarctic ice to search for signals resulting from the interaction of cosmic high-energy neutrinos. She is the principal investigator for the proposed Payload for Ultrahigh Energy Observation (PUEO) experiment, another Antarctic, long-duration balloon mission that would be 10 times more sensitive than ANITA, and the Radio Neutrino Observatory (RNO) in Greenland —a ground-based neutrino search that builds on the Askaryan Radio Array experiment.