Observation of inclined EeV air showers with the radio detector of the Pierre Auger Observatory

AUGER COLLABORATION (VER F. SANCHEZ EN PUBL. ADJUNTA)

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS

IOP PUBLISHING LTD

Lugar: Londres; Año: 2018

1475-7516

With the Auger Engineering Radio Array (AERA) of the Pierre Auger Observa-tory, we have observed the radio emission from 561 extensive air showers with zenith anglesbetween 60deg and 84deg . In contrast to air showers with more vertical incidence, these inclinedair showers illuminate large ground areas of several km 2 with radio signals detectable inthe 30 to 80 MHz band. A comparison of the measured radio-signal amplitudes with MonteCarlo simulations of a subset of 50 events for which we reconstruct the energy using theAuger surface detector shows agreement within the uncertainties of the current analysis. Asexpected for forward-beamed radio emission undergoing no significant absorption or scattering in the atmosphere, the area illuminated by radio signals grows with the zenith angleof the air shower. Inclined air showers with EeV energies are thus measurable with sparseradio-antenna arrays with grid sizes of a km or more. This is particularly attractive as radiodetection provides direct access to the energy in the electromagnetic cascade of an air shower,which in case of inclined air showers is not accessible by arrays of particle detectors on theground.