IACT array performance and design study for multi-TeV gamma-ray astronomy

Abstract

We outline here preliminary performance estimates of an array of modest-sized (24 m2) Cherenkov imaging telescopes for multi-TeV γ-ray astronomy. We have considered an example sparse array of 9 cells of 5 telescopes arranged in a sparsely separated grid, for which the intercell spacing is 1.5 km, and each cell has a side telescope spacing of 500 m. Cosmic-ray background rejection makes use of scaled Hillas-based parameters, and additionaly, we incorporate direction reconstruction exploiting the time development of Cherenkov images, aiming to improve the imaging method at large core distances (typically > 200 m). In the energy range we focus on at present, 10 to 100 TeV, this array provides energy flux sensitivities approaching 3 × 10-13 erg cm-2 s-1, representing a factor 5 to 10 improvement over H.E.S.S. A low altitude (0.2 km) site also provides an improved collection area vs. that obtained at a medium altitude (1.8 km). These preliminary results serve as useful guide in designing a telescope array for multi-TeV astronomy and further improvements in analysis and array design are under investigation. © 2009 American Institute of Physics.