This proposal requests continued support for the University of Chicago group to participate in the building and operation of the Very Energetic Radiation Imaging Telescope Array System (VERITAS). VERITAS is an array of four 12m aperture reflector telescopes for gamma-ray astronomy in the ~50 GeV to ~50 TeV energy range. These atmospheric Cerenkov telescopes use the imaging technique developed by the Whipple Observatory that detected the first galactic and extragalactic sources of TeV gamma-rays. VERITAS will achieve more than an order of magnitude better sensitivity than Whipple with a significant reduction in energy threshold.
Using stereoscopic imaging, the array will achieve unprecedented angular and energy resolution and background rejection over three decades of energy. The primary scientific objectives of VERITAS are the study of active galactic nuclei, supernova remnants, pulsars, gamma-ray bursts, and the search for new sources. While other arrays of gamma-ray telescopes have become active in the last few years, VERITAS remains the most powerful instrument for observations in the northern hemisphere. The minimum detectable flux sensitivity will be 0.5% of the Crab Nebula at 200 GeV. The angular resolution will be sufficient to map out emission regions in extended sources. Studies suggest that more than 30 supernova remnants and more than 30 active galactic nuclei will be discovered by VERITAS. There are also intriguing indications that sources which are only visible at high energies will be discovered. VERITAS will effectively complement GLAST, the next major high energy gamma-ray telescope in space; together they may solve the problem of the origin of the cosmic radiation while also probing fundamental questions in physics and cosmology.
The broader impacts of the proposed research manifest in a number of ways, including the advancement of astrophysical knowledge through the exploitation of new technology in unexplored measurement windows.
