アイテム詳細

要旨

Very High Energy (VHE) γ-ray astronomy using Imaging Atmospheric Cherenkov Telescopes (IACTs) is entering an era of hybrid arrays (such as H.E.S.S. II and CTA), comprising telescopes of varied specifications to enhance the accessible energy range and angular resolution. New algorithms for telescope optical efficiency calibration are developed and adapted for multi-type arrays, for both absolute light yield calibration using muons, and for relative calibration through comparison of shower images. In comparison to previous methods, the stability and flexibility of these algorithms are considerably improved. These will play an important role for the future CTA observatory. The use of multi-type IACT arrays in providing an increased understanding of astrophysical objects and environments is demonstrated through an in-depth study of the Pulsar Wind Nebula HESS J1825-137, known to be highly extended with the presence of strong energy dependent morphology. In particular, measurements of HESS J1825-137 across the entire available energy range allow the particle transport inside the nebula to be constrained, favouring advection over diffusion as the dominant mechanism. Together with X-ray data, a map of the magnetic field of the nebula can be made through spectral modelling. It will also be shown that HESS J1825-137, at 100 pc across, is one of the biggest pulsar wind nebulae to have been discovered yet.