The High Energy Stereoscopic System (H.E.S.S.) - an array of four Imaging Atmospheric Cherenkov Telescopes located in the Khomas highlands of Namibia - explores the nonthermal universe by means of very-high-energy (VHE;>100GeV) [gamma]-ray emission. Its high sensitivity and large field-of-view make it the ideal instrument for a survey of the Milky Way in VHE [gamma]-rays. The H.E.S.S. Galactic Plane Scan resulted in the most complete view of our Galaxy achieved so far in this energy regime. The results of this extensive survey will be presented in this work. From the 45 VHE [gamma]-ray sources detected so far within the Galactic Plane, a short summary is given for the 19 sources detected within the framework of this thesis and three representative sources were analyzed in even more detail: HESS J1912+101 was detected in the vicinity of an energetic pulsar, suggesting a pulsar wind nebula origin of the [gamma]-ray emission. A clear signal of VHE [gamma]-ray emission was also detected from RCW 86, a well-known shell-type supernova remnant. And finally, HESS J1708-441 was discovered in the vicinity of the well known pulsar PSR B1706-44, but cannot be clearly associated with this strong counterpart. As the energy spectra of these sources yield most valuable information about the processes at work in the underlying astrophysical objects, extensive studies of the spectral extraction method were performed to ensure their correct determination.

The current generation of ground-based instruments has rapidly extended the limits of the range accessible to us with very-high-energy (VHE) gamma-rays, and more than a hundred sources have now been detected in the Milky Way. These sources represent only the tip of the iceberg, but their number has reached a level that allows population studies. In this work, a model of the global population of VHE gamma-ray sources based on the most comprehensive census of Galactic sources in this energy regime, the H.E.S.S. Galactic plane survey (HGPS), will be presented. A population synthesis approach was followed in the construction of the model. Particular attention was paid to correcting for the strong observational bias inherent in the sample of detected sources. The methods developed for estimating the model parameters have been validated with extensive Monte Carlo simulations and will be shown to provide unbiased estimates of the model parameters. With these methods, five models for different spatial distributions of sources have been ...

This book provides a theoretical and observational overview of the state of the art of gamma-ray astrophysics, and their impact and connection with the physics of cosmic rays and neutrinos. With the aim of shedding new and fresh light on the problem of the nature of the gamma-ray sources, particularly those yet unidentified, this book summarizes contributions to a workshop that continues today.

This book summarizes the science to be carried out by the upcoming Cherenkov Telescope Array, a major ground-based gamma-ray observatory that will be constructed over the next six to eight years. The major scientific themes, as well as core program of key science projects, have been developed by the CTA Consortium, a collaboration of scientists from many institutions worldwide.CTA will be the major facility in high-energy and very high-energy photon astronomy over the next decade and beyond. CTA will have capabilities well beyond past and present observatories. Thus, CTA's science program is expected to be rich and broad and will complement other major multiwavelength and multimessenger facilities. This book is intended to be the primary resource for the science case for CTA and it thus will be of great interest to the broader physics and astronomy communities. The electronic version (e-book) is available in open access.