The sensitivity of the Durham mk6 ground-based atmospheric cherenkov telescope to very high energy gamma-ray sources

Abstract

The subject of this thesis is a determination of the sensitivity of the Durham Mk6 ground based Imaging Atmospheric Cherenkov Telescope (lACT), an instrument which uses the imaging atmospheric Cherenkov technique to detect Very High Energy (VHE) gamma-rays. The first three chapters are introductory: Chapter 1 describes the basics of Very High Energy (VHE) gamma ray astronomy. Chapter 2 describes the properties of Extensive Ak Showers (EAS). Chapter 3 describes the detection of these EAS on the ground by lACTs, Chapter 4 details the Durham Mk6 lACT and includes a description of the Cherenkov imaging technique for background discrimination. Chapter 5 describes the MOCCA and SOLMK simulation codes. Chapter 6 contains a description of the details of the simulations produced for this diesis. This chapter continues to its logical conclusion and presents a revised VHE gamma-ray flux of 2.5 ± 0.7(_stat) [+0.5 or -1.6](_syst x lO(_7) photons m(^-2) s(^-1) for a sub set of a previously published data set which gave a 6.8σ detection of the close X-ray selected BL Lac PKS 2155-304. Chapter 7 discusses the importance of PKS 2155- 304 and presents 3σ flux limits for another seven Southern hemisphere AGN observed between 1996 and 1999 using the Durham Mk6 IACT. Finally there is a short discussion on the future of VHE gamma-ray astronomy.