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The Galactic Gamma-Ray Source Population between 10 GeV and 50 TeV

Donath, Axel

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Abstract

This work studies the population of Galactic gamma-ray sources between 10 GeV and 50 TeV. In the first part the data taken by the H.E.S.S. Galatic Plane Survey (HGPS) above ∼ 200 GeV is re-analysed using a Poisson Maximum Likelihood based detection method. In this process a catalog of gamma-ray sources as well as a model of the large-scale emission in the Galaxy is created. In total 78 individual sources are detected, of which 31 can be clearly identified. For the remaining objects possible associations with known pulsar wind nebulae, supernova remnants and energetic pulsars are listed. The investigation of the whole source population reveals a variety of objects, that cover a size range from point source up to radii ∼ 1◦. The measured fluxes range from 0.6% to 103% of the flux of the Crab Nebula. The analysis of the longitude, latitude and Log N – Log S distribution of the sources shows a picture of the population that is compatible with the distribution of energetic pulsars, supernova remnnants and CO Gas in the Galaxy. The completeness of this picture is currently limited by the sensitivity of the telescopes. In the second part of this work the results from the HGPS analysis are systematically compared to high-energy observations of the Fermi-LAT satellite. For this purpose images in three energy bands are computed (10 - 30 GeV, 30 -100 GeV und 100 - 2000 GeV) from the Fermi-LAT data and combined into colored RGB images. The qualitative comparison of the images as well as image-based flux profiles against the HGPS measurement shows good agreement in many regions. Individual regions with differences are then discussed in detail. The systematic measurement of fluxes of HGPS sources in the range between 10 GeV and 2 TeV yields significant emission for 55 objects, among 9 objects previously not known as GeV sources. A detailed examination of those cases shows source confusion on the GeV side as limiting factor for the detection.

Item Type: Dissertation
Supervisor: Hofmann, Prof. Dr. Werner
Date of thesis defense: 30 May 2018
Date Deposited: 07 Mar 2019 09:35
Date: 2019
Faculties / Institutes: The Faculty of Physics and Astronomy > Dekanat der Fakultät für Physik und Astronomie
Subjects: 520 Astronomy and allied sciences
Controlled Keywords: Gammaastronomie, Himmelsduchmusterung, Gammastrahlung, Galaxie
Uncontrolled Keywords: H.E.S.S., Pulsarwindnebel, Supernovaüberrest
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