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Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA
P W Gorham1, J Nam2, A Romero-Wolf3
1Department of Physics and Astronomy, University of Hawaii, Manoa, Hawaii 96822, USA.
Physical Review Letters
|August 27, 2016
Summary
Four unusual cosmic-ray (CR) events were detected by the Antarctic Impulsive Transient Antenna (ANITA). Three events were stratospheric air showers, while a fourth suggests a potential tau-lepton decay originating from the ice.
Area of Science:
- High-energy astrophysics
- Particle physics
- Radio astronomy
Background:
- The Antarctic Impulsive Transient Antenna (ANITA) detects radio signals from cosmic-ray (CR) air showers.
- Previous ANITA flights have identified stratospheric CR events.
Purpose of the Study:
- To report on the characteristics of four unusual radio-detected cosmic-ray or CR-like events.
- To investigate the origin of these anomalous events, including a potential tau-lepton decay.
Main Methods:
- Observation of radio signals using the ANITA balloon payload.
- Analysis of stratospheric cosmic-ray air showers.
- Investigation of an upward-pointing radio event with characteristics suggesting an origin from the ice surface.
Main Results:
- Three stratospheric cosmic-ray air showers were detected at altitudes of 20-30 km.
- A fourth event, detected during the ANITA-I flight, was steeply upward-pointing and CR-like.
- The fourth event's characteristics are consistent with a primary particle emerging from the ice, possibly indicating a tau-lepton decay.
Conclusions:
- The observed events provide insights into the behavior of high-energy cosmic rays and potential new physics.
- The upward-pointing event suggests a possible tau-lepton decay, though this requires a significant suppression of the standard model tau-neutrino cross-section.
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