2010/05/12 by S. Hoover, J. Nam, P. W. Gorham +42 · 1 citation
Physics and Astronomy · #astro-ph.HE #astro-ph.IM
paper · pdf · doi:10.1103/physrevlett.105.151101
published as Phys.Rev.Lett.105:151101,2010 · 5 pages, 5 figures, new figure added
arxiv created 2010/05/12 · arxiv updated 2015/03/16
We report the observation of sixteen cosmic ray events of mean energy of 1.5 x 1019 eV, via radio pulses originating from the interaction of the cosmic ray air shower with the Antarctic geomagnetic field, a process known as geosynchrotron emission. We present the first ultra-wideband, far-field measurements of the radio spectral density of geosynchrotron emission in the range from 300-1000 MHz. The emission is 100% linearly polarized in the plane perpendicular to the projected geomagnetic field. Fourteen of our observed events are seen to have a phase-inversion due to reflection of the radio beam off the ice surface, and two additional events are seen directly from above the horizon.