Achieving diffraction limited imaging with an Imaging Air Cherenkov Telescope

Abstract

We propose a method to transform a Cherenkov telescope, primarily designed for gamma-ray astronomy, into an imaging telescope at the diffraction limit of an equivalent astronomical telescope. The method can be applied onto existing and planned Cherenkov telescopes, both taken as a single dish or a set of such telescopes configured for aperture synthesis operating as intensity interferometers. We examine the sensitivity of our method by performing extensive numerical simulations including two and three point correlations, for amplitude and closure phase quantities permitting image reconstruction of stellar surfaces with subtle structures in the range of milli-arc-second resolutions. As a case of study we apply our method to a single 20m class Cherenkov telescope with the perspective of its generalization to the diluted Cherenkov Telescope Array (CTA) under construction in North and South hemispheres.