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Fakultät für Physik - Digitale Hochschulschriften der LMU - Teil 02/05 Podcast
Observation of Galactic Sources of Very High Energy Gamma-Rays with the MAGIC Telescope

Observation of Galactic Sources of Very High Energy Gamma-Rays with the MAGIC Telescope

Fakultät für Physik - Digitale Hochschulschriften der LMU - Teil 02/05 vor 19 Jahren

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One of the most important 'messengers' of many high energy
phenomena in our universe are gamma-rays. The detection of very
high energy (VHE) cosmic gamma-radiation by ground-based Cherenkov
telescopes has opened a new window to the Universe, called
gamma-ray astronomy. It is a rapidly expanding field with a wealth
of new results, particularly during the last two years, due to the
high sensitivity of a new generation of instruments. The major
scientific objective of gamma-ray astronomy is the understanding of
the production, acceleration and reaction mechanisms of very high
energy particles in astronomical objects. This is tightly linked to
the search for sources of the cosmic rays. The MAGIC (Major
Atmospheric Gamma-ray Imaging Cherenkov) telescope is one of the
new generation of Imaging Air Cherenkov Telescopes (IACT) for VHE
gamma-ray astronomy. With its 17 m diameter mirror the MAGIC
telescope is today the largest operating single-dish IACT. It is
located on the Canary Island La Palma (28.8 deg. N, $17.8 deg. W,
2200 m asl.). Recently, eight new galactic VHE gamma-ray sources
were detected by the HESS collaboration. They have either no or
very weak counter-parts in other wavelengths. This makes them ideal
candidates for accelerators of hadronic cosmic rays. The Galactic
Center was also found to be a source of VHE gamma-rays by various
groups. However, the reported spectra differed significantly such
that the nature of the source could not yet be identified.In this
thesis, observations of three galactic sources of VHE gamma-rays
with the MAGIC telescope are discussed: the source at the Galactic
Center and two sources in the galactic disc HESS J1813-178 and HESS
J1834-087. The positions, extensions, morphologies and the
differential fluxes of these sources are presented using the data
from the MAGIC telescope, and possible flux variations with time
are studied. To identify the gamma-ray production mechanism and the
nature of the sources, the gamma-ray sources are related to
possible counter-parts in other wavelength bands. For HESS
J1813-178, leptonic and hadronic models for the multiwavelength
emission are developed and compared to the data to identify the
physical processes at work in the source. The source at the
Galactic Center is shown to be a stable emitter of VHE gamma-rays,
and the implications for the source models are discussed. As these
sources are located in the southern sky and can only be observed
under large zenith angles with the MAGIC telescope, suitable
observation and analysis procedures for large zenith angles had to
be developed. In order to achieve the best possible background
determination, the sources were observed in the off-source tracking
observation mode. To further increase the sensitivity of the MAGIC
telescope, new ultra-fast read-out electronics components have been
developed as an upgrade project for the MAGIC telescope. The
performance of the new system is evaluated based on prototype tests
in the MAGIC telescope at La Palma. The production, tests, and
installation on the MAGIC telescope of a full-scale read-out system
are described.