Current Status and New Challenges of The Tunka Radio Extension

Abstract

The Tunka Radio Extension (Tunka-Rex) is an antenna array spread over an area of about 1 km 2 . The array is placed at the Tunka Advanced Instrument for cosmic rays and Gamma Astronomy (TAIGA) and detects the radio emission of air showers in the band of 30 to 80 MHz. During the last years it was shown that a sparse array such as Tunka-Rex is capable of reconstructing the parameters of the primary particle as accurate as the modern instruments. Based on these results we continue developing our data analysis. Our next goal is the reconstruction of cosmic-ray energy spectrum observed only by a radio instrument. Taking a step towards it, we develop a model of aperture of our instrument and test it against hybrid TAIGA observations and Monte-Carlo simulations. In the present work we give an overview of the current status and results for the last five years of operation of Tunka-Rex and discuss prospects of the cosmic-ray energy estimation with sparse radio arrays. * now at the University of Zürich †also at Vrije Universiteit Brussel, Belgium

Seven years of Tunka-Rex operation

“…Seven years of Tunka-Rex operation D. Kostunin we have reached the precision for the primary energy of up to 10% and of up to 25 g/cm 2 for the depth of the shower maximum [25]. Combining improved reconstruction with the estimation of efficiency and exposure [26,27] we have obtained averaged shower maxima and cosmic ray flux as a function of primary energy. In Fig.…”

Estimation of aperture of the Tunka-Rex radio array for cosmic-ray air-shower measurements

“…To account for the uncertainty of the signal description, we apply a marginalization procedure. The function under the marginalization is a combination of the probability density of signal detection (6) and the probability density of appeared signal strength modeled with the normal distribution, N , with the standard deviation equal to 15% found from the comparison of the model and the simulations, = 0.15 . The combined density is subject to marginalization over the signal strength…”

“…The solutions for these two integrals are known, the details of the derivation are in Ref. [6]. The solution for the aperture has the form…”

Modeling the Aperture of Radio Instruments for Air-Shower Detection

“…Estimation of the integral can introduce additional uncertainties on the level of several percent, and requires using the PoS(ICRC2019)331 special methods [4]. Also, it was shown recently that there is a way to evaluate the integral semianalytically for the full efficiency regions [5]. Evaluation of these methods in application is subject for further studies.…”