E.B. Postnikov, A.A. Grinyuk, L.A. Kuzmichev, L.G. Sveshnikova, L.G. Tkachev

Primary gamma ray selection technique in the joint operation of Imaging Atmospheric Cherenkov Telescopes (IACTs) and wide angle Cherenkov timing detectors

This presentation is a methodical study on hybrid reconstruction techniques for hybrid imaging timing Cherenkov observations. Until now the main results in TeV and sub TeV energy region were obtained via stereoscopic systems of Imaging Atmospheric Cherenkov Telescopes (IACT). The international Gamma-observatory TAIGA (Tunka Advanced Instrument for cosmic rays and Gamma-Astronomy) is intended for ultra high energy gamma-ray astronomy (>30 TeV). It aims at combining the cost-effective timing-array technique with IACTs, allowing to reach a total area up to a few square kilometers and strong suppressing hadron background because of a very precise angular resolution (order of 0.1 degrees at the energy >100 TeV). Hybrid operation of both of these techniques can lead to a relatively cheap way of development of a large area array. This type of hybrid timing/imaging array is to be realized for the first time ever. The joint approach of gamma events selection was investigated on both type of simulated data: the image parameters from the IACT, and the shower parameters reconstructed from the timing array. The report contains answers to various important questions: the optimal set of imaging and timing parameters to be combined; the efficiency of the multivariate approach; hadron suppression factor value depending on distance and energy; hadron suppression improvement with the comparison of a separate use of the IACT (without the timing array); etc. We show that the hadron suppression about 100 times is to be achieved on a distance up to 450 m for the energy greater than 50 TeV.