The study of the Seyfert galaxy NGC 4151 with the scintillation imaging gas-filled hard X-ray telescope (SIGHT)

The purpose of research in high energy astrophysics is to understand the nature of astronomical sources of high energy radiation. Unfortunately, this understanding is often limited by the quality and relative scarcity of the data available as compared to lower energy measurements. Since hard X-ray and gamma-ray telescopes must be placed above the Earth's atmosphere, observation times are limited. X-ray and gamma-ray sources are typically rather weak and the sensitivity of the telescopes used to observe them is usually much lower than the sensitivity of the telescopes used at lower energies. Improvements in the sensitivity, energy resolution and imaging capabilities of hard X-ray detectors can make a significant difference in the understanding of the astrophysical sources observed. It is therefore very important that new X-ray and gamma-ray detector technologies be developed. For example, while the present understanding of the central power source in the Seyfert galaxy NGC 4151 is limited by the number and the quality of the X-ray and gamma-ray observations, recent measurements with improved instrumentation are proving very useful. This dissertation presents the Scintillation Imaging Gas-filled Hard X-ray Telescope (SIGHT) as a new hard X-ray telescope for improved 30-300 keV observations and discusses its use for further investigation into the nature of the central power source in NGC 4151. The dissertation begins with a review of the observations and present understanding of the X-ray emission from NGC 4151. The SIGHT telescope is described in detail, the instrument's sensitivity is calculated and a Monte Carlo detector simulation program is discussed. The dissertation concludes with an investigation of how SIGHT may be used to make high quality observations of NGC 4151 and thus improve the present understanding of the source's hard X-ray emission.