[PDF] Gamma Ray Astrophysics The Extragalactic Background Light And New Physics eBook

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Publisher :
Page : 6 pages
File Size : 19,13 MB
Release : 2008
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ISBN :

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Very high energy gamma-rays are expected to be absorbed by the extragalactic background light over cosmological distances via the process of electron-positron pair production. However, recent observations of cosmologically distant emitters by ground based gamma-ray telescopes might be indicative of a higher-than-expected degree of transparency of the universe. One mechanism to explain this observation is the oscillation between photons and axion-like-particles (ALPs). Here we explore this possibility, focusing on photon-ALP conversion in the magnetic fields in and round gamma-ray sources and in the magnetic field of the Milky Way, where some fraction of the ALP flux is converted back into photons. We show that this mechanism can be efficient in allowed regions of the ALP parameter space, as well as in typical configurations of the Galactic Magnetic Field. As case example, we consider the spectrum observed from a HESS source. We also discuss features of this scenario which could be used to distinguish it from standard or other exotic models.

Author : Volker Schönfelder
Publisher : Springer Science & Business Media
Page : 418 pages
File Size : 15,28 MB
Release : 2013-03-14
Category : Science
ISBN : 3662045931

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After describing cosmic gamma-ray production and absorption, the instrumentation used in gamma-ray astronomy is explained. The main part of the book deals with astronomical results, including the somewhat surprising result that the gamma-ray sky is continuously changing.

Author : T.C. Weekes
Publisher : CRC Press
Page : 234 pages
File Size : 44,4 MB
Release : 2003-04-08
Category : Science
ISBN : 1420033190

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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

Author : P. V. Ramana Murthy
Publisher : Cambridge University Press
Page : 275 pages
File Size : 32,48 MB
Release : 1993-04
Category : Nature
ISBN : 0521420814

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The recent launch of NASA's Gamma-Ray Observatory will increase interest in gamma-ray astronomy. This is a fully up-dated new edition of the authors' earlier volume published in 1986 and covers both the background science and the current state-of-the-art in this field. The emphasis is on the astronomy and astrophysics of known sources of cosmic gamma-rays outside the solar system. The authors discuss the mechanisms for the production and absorption of gamma-rays. The gamma-ray line astronomy of the interstellar medium, galactic centre, and various discrete sources is then considered. Gamma-ray bursts are treated in considerable detail in chapter three, and the final two chapters describe medium energy and ultra-high energy gamma-rays. Relevant data from supernova SN1987A is also included in this edition. The book includes comprehensive references to the primary literature, together with many figures and tables. The concentration on phenomenology makes this book a fine introduction to gamma-ray astronomy.

Author : K.S. Cheng
Publisher : Springer Science & Business Media
Page : 412 pages
File Size : 44,13 MB
Release : 2012-11-03
Category : Science
ISBN : 1402022565

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Gamma-ray astronomy has undergone an enormous progress in the last 15 years. The success of satellite experiments like NASA's Comp ton Gamma-Ray Observatory and ESA's INTEGRAL mission, as well as of ground-based instruments have open new views into the high-energy Universe. Different classes of cosmic gamma-ray sources have been now detected at different energies, in addition to young radio pulsars and gamma-ray bursts, the classical ones. The new sources include radio quiet pulsars, microquasars, supernova remnants, starburst galaxies, ra dio galaxies, flat-spectrum radio quasars, and BL Lacertae objects. A large number of unidentified sources strongly suggests that this brief enumeration is far from complete. Gamma-ray bursts are now estab lished as extragalactic sources with tremendous energy output. There is accumulating evidence supporting the idea that massive stars and star forming regions can accelerate charged particles up to relativistic ener gies making them gamma-ray sources. Gamma-ray astronomy has also proved to be a powerful tool for cosmology imposing constraints to the background photon fields that can absorb the gamma-ray flux from dis tant sources. All this has profound implications for our current ideas about how particles are accelerated and transported in both the local and distant U niverse. The evolution of our knowledge on the gamma-ray sky has been so fast that is not easy for the non-specialist scientist and the graduate student to be aware of the full potential of this field or to grasp the fundamentals of a given topic in order to attempt some original contribution.

Author : Denis Bastieri
Publisher : American Institute of Physics
Page : 260 pages
File Size : 39,91 MB
Release : 2009-05-15
Category : Science
ISBN :

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This is the sixth edition in a series of Workshops on High Energy Gamma-Ray Experiments, following the ones held in Perugia (2002), Bari (2004), Cividale del Friuli (2005), Elba Island (2006) and Villa Mondragone (2007). The year the focus is on the region known by the acronym VHE (Very High Energy), bridging the gap between GeV and TeV. The physics that lies in this region is of the utmost importance to improve our knowledge of many different astrophysical sources like pulsars, AGNs, GRBs, and our understanding of the main components of the Extragalactic Background Light (EBL). An update is given on the current and planned research for spaceborne and ground-based experiments dedicated to the observation of the gamma-ray sky.

Author : K.E. Turver
Publisher : Springer
Page : 308 pages
File Size : 19,35 MB
Release : 2011-09-26
Category : Science
ISBN : 9789401082051

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An Advanced Research Workshop on Very High Energy Gamma Ray Astronomy and Related Topics was held at Durham, England during August 11-15 1986. The meeting was sponsored by the Scientific Affairs Division of NATO and the University of Durham. It is four years since the first Workshop dedicated to High Energy Gamma Ray Astronomy was held at Ootacamund, India. At that meeting the developments in Very High Energy Gamma Ray Astronomy over a period of more than 20 years were reported and the methodology, limitations, improvements and prospects for further progess were discussed. The possible requirement for a follow-up meeting was clear if the optimistic future foreseen for the field at the Ooty meeting was correct. The Durham meeting was suggested to fill this role. Although the arrangements for the Durham meeting were discussed as long ago as 1983 with possible dates in 1984 or 1986, the eventual date in 1986 has proved admirable and has coincided with a time when further advances have been reported. An important feature of the proposal for the Durham meeting was the emphasis on a series of Workshop sessions, the conclusions of each to be summarized by a Rapporteur. The purpose of these sessions was to provide a consensus view of many of the important areas in the field at a time of increasing interest by the rest of the astrophysics community.

Author : Josep M. Paredes
Publisher : Springer Science & Business Media
Page : 496 pages
File Size : 19,37 MB
Release : 2007-07-17
Category : Science
ISBN : 1402061188

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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.

Author : Chryssa Kouveliotou
Publisher : Cambridge University Press
Page : 361 pages
File Size : 11,14 MB
Release : 2012-11-22
Category : Nature
ISBN : 0521662095

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A comprehensive graduate-level review of GRB astrophysics and its history, featuring the latest research by an international team of experts.