2016/03/31 by P. W. Gorham, J. Nam, A. Romero-Wolf +66 · 1 citation
Physics and Astronomy · #astro-ph.HE
paper · pdf · doi:10.1103/physrevlett.117.071101
published as Phys. Rev. Lett. 117, 071101 (2016) · 5pp,4 figures, referees' comments addressed, this version accepted to Phys. Rev. Letters. Supplemental PDF material available; see source files
arxiv created 2016/06/29 · arxiv updated 2016/08/17
We report on four radio-detected cosmic-ray (CR) or CR-like events observed with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload. Two of the four were previously identified as stratospheric CR air showers during the ANITA-I flight. A third stratospheric CR was detected during the ANITA-II flight. Here we report on characteristics these three unusual CR events, which develop nearly horizontally, 20-30~km above the surface of the Earth. In addition, we report on a fourth steeply upward-pointing ANITA-I CR-like radio event which has characteristics consistent with a primary that emerged from the surface of the ice. This suggests a possible τ-lepton decay as the origin of this event, but such an interpretation would require significant suppression of the Standard Model τ-neutrino cross section.