Particle Astrophysics with VERITAS

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

This proposal is to support researchers at the University of California, Los Angeles (UCLA) to participate in the VERITAS gamma-ray telescope project. VERITAS (Very Energetic Radiation Imaging Telescope Array System) consists of four atmospheric Cherenkov telescopes presently under construction at a mountain site in southern Arizona. Mounted in the focal plane of each telescope is an array of fast light detecting sensors. VERITAS detects high-energy gamma rays from the products of their interactions in the atmosphere. A gamma-ray creates a shower of particles in the atmosphere, most of which are moving faster than the speed of light in air. These particles radiate Cherenkov light that propagates to the ground in a short flash. For very brief periods of time (few nanoseconds), this flash is brighter than the night sky background light, allowing VERITAS to detect them on clear, moonless nights. The field of very high-energy gamma-ray astronomy has been revolutionized in the last decade by discoveries made by NASA's Compton Gamma Ray Observatory in space and by ground-based Cherenkov telescopes built with support from the National Science Foundation and the Department of Energy. We have discovered many new sources that produce very high-energy radiation, including active galaxies, gamma-ray bursts, supernova remnants, and pulsars. The energies in the detected gamma rays are comparable to or exceed the energies produced in man-made accelerators. Thus the astrophysics sources typically involve harnessing the enormous energies contained near black holes or energies produced in the explosions of massive stars. In spite of these exciting discoveries, however, there is still a great deal that we do not understand - for example, we do not fully understand how these extremely violent systems work, and to date only a few percent of the overhead sky has been surveyed with sensitivity. VERITAS represents a major step forward in our ability to detect and understand the sources of these very high-energy particles. The VERITAS array will be able to discover sources that are ten times fainter than previously detected. The fact that each Cherenkov shower will be viewed by multiple telescopes greatly improves the telescope's ability to determine the direction and energy of the incoming gamma ray. VERITAS' four telescopes will be constructed between 2003 and 2006. When completed, VERITAS will be the most sensitive instrument ever built for astronomy at these wavelengths. The UCLA group is playing a major role in the construction of VERITAS, participating in the development of the electronics to read out the telescope sensors and in the development of computer software to analyze the telescope data and to simulate the telescope performance. Our efforts will involve both graduate students and postdoctoral research associates. In addition, UCLA will have a major involvement in the VERITAS Outreach Program, which is currently under development.