Aartsen, and 335 co-authors, reported in 2020 that the recent detections of events of interest by ANITA are considered anomalous due to the small survival probability of EeV tau-neutrinos through long chord lengths. The events are known to be inconsistent with a cosmogenic interpretation, but could have been produced by cosmic accelerators, specifically those with short characteristic timescales. We show here that for timescales as small as 103 s, assuming AAE-141220 as originating from a neutrino source, limits set using IceCube data are more than four orders of magnitude in tension with the point source flux required to detect one event at ANITA. These limits are constraining for a variety of flux models, from simple power laws to any generic model that includes a component at or above EeV energies.
In addition to the anomalous events, the authors also find no evidence for a neutrino source in the direction of the neutrino candidate event from a search for Askaryan emission during ANITA-III. These new limits, in conjunction with the inconsistency of isotropic flux interpretations, leave no room for an astrophysical interpretation of the AAE in the context of the Standard Model. However, it has been shown that these events can be explained using physics Beyond the Standard Model, as many models suggest that the AAE lend support for axionic dark matter, sterile neutrinos, supersymmetry, or heavy dark matter. With the exception of the axionic dark matter explanation, all of these proposed models can be constrained by this non-observation at IceCube, and dedicated tests to quantify these constraints will be the focus of another work.
In addition to explanations that incite new physics, it has recently been suggested that the AAE could be explained by downward-going CR-induced EAS that reflected off of subsurface features in the Antarctic ice (Shoemaker et al. 2019). Another possible explanation could be coherent transition radiation from the geomagnetically-induced air shower current, which could mimic an upgoing air shower. Explaining these anomalous events with systematic effects or confirming the need for new physics requires a deeper understanding of ANITA’s detection volume. Efforts such as the HiCal radio frequency pulser, which has flown alongside ANITA in the last two flights, are already underway to try to characterize the various properties of the Antarctic ice surface.
Also see a more popular version of the paper: (more).
Managed & Built by I2M Consulting, LLC | © 2010-
