Transition radiation model for LF radio emission produced by ultrahigh-energy cosmic rays

Abstract

Wide-band radio emission from cosmic ray-induced extensive air showers is now well established. The electromagnetic component of the extensive air shower, during their propagation through atmosphere, interacts with their surroundings emitting radio pulses which can be detected from the very low frequency to the very high frequency. Conventional detection techniques, although effective, have lower duty cycles and are expensive. The radio method, on the other hand, provides almost 100 % duty cycle after suppressing the radio frequency interferences and is also cost-effective. Correlation studies show that there must be at least two separate mechanisms responsible for radio emission at low and high frequencies. So far, theoretical models based on computer simulations have been successful in explaining the emission at high frequencies. However, at low frequencies, the available theories have been incapable of explaining the observed field strengths as high as ~750 μV/m/MHz. In this paper, a mathematical model based on transition radiation is proposed to explain the low-frequency radio emission that uses realistic particle distribution obtained from the Monte Carlo simulation code CORSIKA.