Cherenkov Telescope Array – the next-generation ground-based gamma-ray observatory
Robert Wagner, University of Stockholm
The past decade has seen a dramatic improvement in the quality of data available at high-energy gamma-rays. The all-sky LAT instrument on board of the Fermi satellite has revealed about 2,000 sources in the sky at the 100 MeV – 100 GeV band, and almost 200 sources have been detected at even higher energies, E>100 GeV, gamma rays energies by pointed, ground-based Imaging Air Cherenkov Telescopes.
These so-called very high-energy (VHE) gamma rays gamma rays cannot be produced in thermal processes, but are produced by interactions of high-energy particles. Gamma rays thus trace populations of such particles and enable the cosmic particle accelerators to be imaged and studied. Gamma-ray emitting particle accelerators are ubiquitous in the Galaxy and beyond; they include a variety of galactic and extragalactic objects. Details of the acceleration mechanisms as well as the role high-energy particles play in the evolution of star forming systems and galaxies remain to be fully understood. Gamma-rays can also be used as probes of the physics of the early universe, of fundamental physics, and could be products of dark matter annihilation in some cold dark matter realizations.
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(The slides will be available after the talk)
I will briefly introduce the IACT technique and then discuss CTA, the new ground-based observatory for very high-energy (VHE, E>30 GeV) gamma rays. CTA has ambitious science goals, for which it is necessary to improve the flux sensitivity by about an order of magnitude, but also the angular and energy resolutions, over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1,500 members from 29 countries in Europe, Asia, Africa and the Americas. I will present the overall design and the planned schedule of the project. I will also discuss the current status of the high-energy gamma-ray astrophysics, some of the key results obtained in the last 15 years, and the prospects for studies with CTA.