A Search for Gamma Ray Emission from the Region of the Galactic Center PDF Download

Author: Glen Hamilton Dahlbacka
Publisher:
ISBN:
Category : Gamma rays
Languages : en
Pages : 288

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Author: Nathan Kelley-Hoskins
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: D.A. Kniffen
Publisher:
ISBN:
Category :
Languages : en
Pages : 29

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Author: E.L. Chupp
Publisher: Springer Science & Business Media
ISBN: 9401014965
Category : Science
Languages : en
Pages : 332

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Observation of discrete energy electromagnetic emissions from celestial objects in the radio, IR, optical, lN, and X-ray spectral regions has dramatically advanced our know ledge in the field of astrophysics. It is expected that identification of nuclear 'Y-ray line emissions from any cosmic source would also prove to be a powerful new tool for probing the Universe. Since the publication of Morrison's work in 1958, many experiments were carried out searching for evidence of 'Y-ray lines from cosmic sources, however with little success. Only a few positive experimental results have been reported, in spite of an expenditure of considerable effort by many people: in particular, the possible Galactic Center emission line (473 to 530keV) and 'Y-ray lines at several energies (e. g. , 0. 5 MeV and 2. 2 MeV) associated with large solar flares. Both of these observations are unconfirmed by indepen dent observations (ca. 1975). The high energy 'Y-rays (>30MeV) from the Galactic Center are at least partly due to the decay of 1[0 mesons, which are of unique energy (67. 5 MeV) in the 1[0 rest frame only. The reasons for the limited amount of data avail able in this field, even though early theoretical predictions were very optimistic regarding fluxes of nuclear lines, are that experimental efforts are plagued with high backgrounds and low fluxes, and that development of instruments with telescopic properties in the energy range of interest is difficult.

Author: Fulvio Melia
Publisher: Princeton University Press
ISBN: 9780691131290
Category : Science
Languages : en
Pages : 324

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Author: Carl E. Fichtel
Publisher:
ISBN:
Category : Gamma ray astronomy
Languages : en
Pages : 432

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The High Energy Stereoscopic System, H.E.S.S., is an array of four imaging atmosphericCherenkov telescopes, located in the Khomas highlands of Namibia, designed for the exploration of very high-energy (E> 100 GeV) gamma-ray emission in the universe, arising in non-thermal processes. Its location in the southern hemisphere renders sensitive observations of a large region of the Galactic Plane possible. In particular, a deep exposure of the Galactic Center region allows detailed studies of the observed emission, helping to identify the sources of the radiation and the physics processes at play. In this thesis, new methods are developed to study both the morphological and spectral properties of diffuse very high-energy gamma-ray emission from the Galactic Center region. Assuming that the radiation originates from hadronic interactions of diffusing cosmic rays with the ambient matter, this study helps to constrain the parameter space of cosmic-ray diffusion in the Galactic Center region. The second part of this work introduces new methods to search for signals of Dark Matter annihilations, putting upper-limits on the production of spectral line features in the H.E.S.S. Galactic Center data. Finally, an upper-limit on the total annihilation cross-section of Dark Matter particles is derived.

Author: M. Signore
Publisher: Springer Science & Business Media
ISBN: 9401100675
Category : Science
Languages : en
Pages : 422

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This volume consists of invited lectures and seminars presented at the NATO Advanced Study Institute "The Gamma Ray Sky with COMPTON GRO and SIGMA" , which was held at the Centre de Physique Theorique of Les Houches (France) in January / February 1994. The school has been planned by a Scientific Organizing Committee. It was organized with the aim of providing students and young researchers with an up-to-date account of the high-energy phenomena in the vicinity of compact objets and the diffuse gamma-ray backgrounds after the early results from the gamma-ray telescope SIGMA and the four instruments onboard COMPTON GRO (Gamma Ray Observatory) : BATSE (Burst and Transient Source Experiment),COMPTEL(Compto'l Telescope),EGRET (Energetic Gamma Ray Experiment Telescope) and OS SE(Oriented Scintillation Spectrometer Experiment) . It was attended by more than sixty researchers from many countries. The lectures and seminars represent a complete coverage of our present knowledge and understanding of: Gamma-ray backgrounds, Gamma-ray Burts,Active Galactic Nuclei,Galactic Compact Objects, Gamma-ray Spectroscopy, Instrumentation and observation techniques, etc ... Most of these lectures are reproduced in this volume. Unfortunately, a few lecturers have chosen not to submit their manuscript.

Author: Wang Ping
Publisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 167

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This thesis focuses on the search for unknown dark matter (DM) satellites in the Milky Way using the Fermi Large Area Space Telescope (LAT). The Fermi Gamma-ray Space Telescope (Fermi) is a next generation space observatory, which was successfully launched on June 11th, 2008. The LAT is the principal scientific instrument onboard. Its unprecedented angular resolution and sensitivity in the 100 MeV to > 300 GeV energy range makes it an excellent instrument for probing the sky for DM satellites. Current N-body simulations based on the Lambda-CDM cosmology model predict a large number of as yet unobserved DM satellites in our galaxy; some satellites are predicted to be extended sources (> 1deg extension) as seen by the LAT. Our work assumes that a significant component of DM is a Weakly Interacting Massive Particle (WIMP) in the 100 GeV mass range. The annihilation of WIMPs results in many high energy gamma rays that can be well measured by the LAT. The WIMP produced gamma-ray spectrum from the putative DM satellites is considerably harder than most astrophysical sources. Also, DM satellites have no astronomical counterparts in the X-ray and radio bands, and the emission has no time variability. My thesis will focus on a blind analysis in the search for unknown DM satellites using one year of LAT data, and setting constraints on some WIMP models based on the results of our analysis in which we find no candidates.

Author: T.C. Weekes
Publisher: CRC Press
ISBN: 1420033190
Category : Science
Languages : en
Pages : 234

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Book Description
High energy gamma-ray photons are the prime probes of the relativistic or high-energy universe, populated by black holes, neutron stars, supernovae, quasars, and matter-antimatter annihilations. Through studying the gamma-ray sky, astrophysicists are able to better understand the formation and behavior of these exotic and energetic bodies. V