Download or read book STACEE Observations of Markarian 421 Above 100 GeV and a New Method for High energy Spectral Analysis written by Jennifer Elaine Carson and published by . This book was released on 2005 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2006 with total page 862 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 300 Gev Observations of Unidentified Egret Sources a Search for TeV Counterparts to Batse Gamma Ray Bursts written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-02 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are few things more intriguing in high energy astrophysics than the study of the highest energy particles in the universe. Where and how these particles achieve their extreme energies is of interest not only to the astrophysicist but also to the particle physicist. At GeV and TeV energies the problem is manageable since the physics is known and the acceleration processes feasible. But the energy spectrum extends to 10(exp 20)Ev and there the problem of their origin is both more difficult and interesting; in fact at these high energies we do not even know what the particles are. The study of the origin and distribution of relativistic particles in the universe has been a challenge for more than 80 years but it is only in recent years that the technology has become available to really address the question. Although something can be learned from studies of composition and energy spectrum, the origins (and thence the acceleration mechanisms) can only come from the direct study of the neutral particle component (in this respect the highest energy particles are effectively neutral since they are virtually undeflected). The feasible channels of investigation are therefore the study of the arrival directions of: (1) TeV photons (covered by the following U.S. experiments: STACEE, Whipple/VERITAS, MILAGRO and, to some extent, by EGRET/GLAST); (2) neutrinos of TeV energy and above (AMANDA/KM3); (3) the highest energy cosmic rays (HiRes, Auger). While these studies represent a form of astronomy they are the astronomy of the extraordinary universe, the universe populated by the most dynamic and physically exciting objects, the universe of the high energy astrophysicist whose cosmic laboratories represent conditions beyond anything that can be duplicated in a terrestrial laboratory. This extraordinary astronomy may say little about the normal evolution of stars and galaxies but it opens windows into cosmic particle acceleration where new and strange physical processes take ...
Download or read book Multiwavelength Observations of Markarian 421 written by Mead Mason Jordan and published by . This book was released on 2004 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gamma ray Burst Observations Above 100 GeV with STACEE written by Alexander Charles Jarvis and published by . This book was released on 2008 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Gamma ray Energy Spectrum of the Active Galaxy Markarian 421 written by Jeffrey Alan Zweerink and published by . This book was released on 1997 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gamma ray Burst Observations at High energy with the Fermi Large Area Telescope written by Aurélien Philippe Bouvier and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fermi Gamma-ray Space Telescope recently celebrated its two-years anniversary in space. With the Large Area Telescope (LAT), its main instrument onboard, Fermi opened a new era in high-energy astrophysics and in particular for the study of Gamma-Ray Bursts (GRBs), which are short flashes of -rays associated with the brightest and most distant events ever observed in our universe after the Big Bang. My thesis work focused primarily on the observations of this phenomenon with the LAT (20 MeV - 300 GeV) and the Gamma-ray Burst Monitor (10 keV - 40 MeV) onboard the Fermi satellite. After describing the procedure used for detection and analysis of LAT GRBs, I will provide an overview of the temporal and spectral features observed during the prompt emission of these events after one year and a half of operation for Fermi. GRBs can also be used as a tool to probe interesting physics. My focus will be on the detection of very high energy photons (typically above 10 GeV) associated with LAT GRBs and which were used to set significant constraints both on a possible violation of Lorentz invariance - which postulates that all observers measure exactly the same speed of light in vacuum, independently of photon energy - and on the Optical-Ultraviolet extragalactic background light in the Universe.
Download or read book Astronomy with Radioactivities written by Roland Diehl and published by Springer Science & Business Media. This book was released on 2010-10-02 with total page 577 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the reader to the field of nuclear astrophysics, i.e. the acquisition and reading of measurements on unstable isotopes in different parts of the universe. The authors explain the role of radioactivities in astrophysics, discuss specific sources of cosmic isotopes and in which special regions they can be observed. More specifically, the authors address stars of different types, stellar explosions which terminate stellar evolutions, and other explosions triggered by mass transfers and instabilities in binary stars. They also address nuclear reactions and transport processes in interstellar space, in the contexts of cosmic rays and of chemical evolution. A special chapter is dedicated to the solar system which even provides material samples. The book also contains a description of key tools which astrophysicists employ in those particular studies and a glossary of key terms in astronomy with radioactivities.
Download or read book The GeV TeV Connection in Galactic Gamma ray Sources written by and published by . This book was released on 2007 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent observations by atmospheric Cherenkov telescopes such as H.E.S.S. and MAGIC have revealed a large number of new sources of very-high-energy (VHE) gamma-rays above 100 GeV, mostly concentrated along the Galactic plane. At lower energies (100 MeV - 10 GeV) the satellite-based instrument EGRET revealed a population of sources clustering along the Galactic Plane. Given their adjacent energy bands a systematic correlation study between the two source classes seems appropriate. While only a few of the sources connect, both in terms of positional coincidence and spectral consistency, most of the detections occur only in one or the other energy domain. In these cases, for the first time consistent upper limits in the other energy band have been derived. Here, the populations of Galactic sources in both energy domains are characterized on observational as well as on theoretical grounds, followed by an interpretation on their similarities and differences. The observational data at this stage suggest rather different major source populations at GeV and TeV energies. With regards to preparations for the upcoming GLAST mission that will cover the energy range bridging GeV and TeV instruments this paper investigates the connection between the population of sources in these bands and concludes with predictions for commonly observable sources for GLAST-LAT detections.
Download or read book Science With The Cherenkov Telescope Array written by The Cta Consortium and published by World Scientific. This book was released on 2018-12-31 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book A New Method for the Reconstruction of Very high energy Gamma ray Spectra and Application to Galactic Cosmic ray Accelerators written by Milton Virgílio Fernandes and published by . This book was released on 2014 with total page 221 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Energy Spectra of GeV TeV Cosmic Ray Leptons written by and published by . This book was released on 2011 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent observations of cosmic ray electrons from several instruments have revealed various degrees of deviation in the measured electron energy distribution from a simple power-law, in a form of an excess around 0.1 to 1 TeV energies. An even more prominent deviation and excess has been observed in the fraction of cosmic ray positrons around 10 and 100 GeV energies. These observations have received considerable attention and many theoretical models have been proposed to explain them. The models rely on either dark matter annihilation/decay or specific nearby astrophysical sources, and involve several additional assumptions regarding the dark matter distribution or particle acceleration. In this paper we show that the observed excesses in the electron spectrum may be easily reproduced without invoking any unusual sources other than the general diffuse Galactic components of cosmic rays. The model presented here assumes a power-law injection of electrons (and protons) by supernova remnants, and evaluates their expected energy spectrum based on a simple kinetic equation describing the propagation of charged particles in the interstellar medium. The primary physical effect involved is the Klein-Nishina suppression of the electron cooling rate around TeV energies. With a very reasonable choice of the model parameters characterizing the local interstellar medium, we can reproduce the most recent observations by Fermi and HESS experiments. Interestingly, in our model the injection spectral index of cosmic ray electrons becomes comparable to, or even equal to that of cosmic ray protons. The Klein-Nishina effect may also affect the propagation of the secondary e{sup {+-}} pairs, and therefore modify the cosmic ray positron-to-electron ratio. We have explored this possibility by considering two mechanisms for production of e{sup {+-}} pairs within the Galaxy. The first is due to the decay of [pi]{sup {+-}}'s produced by interaction of cosmic ray nuclei with ambient protons. The second source discussed here is due to the annihilation of the diffuse Galactic [gamma]-rays on the stellar photon field. We find that high positron fraction increasing with energy, as claimed by the PAMELA experiment, cannot be explained in our model with the conservative set of the model parameters. We are able, however, to reproduce the PAMELA (as well as Fermi and HESS) results assuming high values of the starlight and interstellar gas densities, which would be more appropriate for vicinities of supernova remnants. A possible solution to this problem may be that cosmic rays undergo most of their interactions near their sources due to the efficient trapping in the far upstream of supernova shocks by self-generated, cosmic ray-driven turbulence.
Download or read book Very High Energy Gamma Ray Astronomy written by T.C. Weekes and published by CRC Press. This book was released on 2003-04-08 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Download or read book High Energy Astrophysics written by Malcolm S. Longair and published by Cambridge University Press. This book was released on 2011-02-03 with total page 885 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing students with an in-depth account of the astrophysics of high energy phenomena in the Universe, the third edition of this well-established textbook is ideal for advanced undergraduate and beginning graduate courses in high energy astrophysics. Building on the concepts and techniques taught in standard undergraduate courses, this textbook provides the astronomical and astrophysical background for students to explore more advanced topics. Special emphasis is given to the underlying physical principles of high energy astrophysics, helping students understand the essential physics. The third edition has been completely rewritten, consolidating the previous editions into one volume. It covers the most recent discoveries in areas such as gamma-ray bursts, ultra-high energy cosmic rays and ultra-high energy gamma rays. The topics have been rearranged and streamlined to make them more applicable to a wide range of different astrophysical problems.
Download or read book TeV Gamma Ray Astrophysics written by Heinrich J. Völk and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: The `International Heidelberg Workshop on TeV Gamma-Ray Astrophysics' brought together astrophysicists from the various fields which play a role in the formation of high energy gamma-ray emission. In particular, theoretical and observational aspects of the physics and astrophysics of pulsars and quasars, the acceleration of particles at Supernova Remnants and other strong astrophysical shock fronts, and cascade processes in universal background photon fields were comprehensively discussed in more than thirty reviews by leading experts. In their entirety these reviews describe the birth of a new field of astronomy. This field concerns cosmic gamma-rays of very high energy which are observed with ground-based optical telescopes due to the Cherenkov emission of the secondary particles created by the interaction of these gamma-rays with atoms in the Earth's atmosphere. Beyond that, the workshop encompassed the latest developments and trends in theory and observation of cosmic gamma-ray sources of all energies, from nuclear gamma-ray lines in the MeV-region, through the Bremsstrahlung, Inverse Compton, and pion decay continuum emission, to gamma-rays due the decay of exotic relics from the early Universe. Audience: Specialists as well as students in physics and astrophysics and young research workers.
Download or read book Encyclopedia Of Cosmology The In 4 Volumes written by Rennan Barkana and published by World Scientific. This book was released on 2018-03-16 with total page 1402 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Encyclopedia of Cosmology is a new and exciting project which will be a major, long-lasting, seminal reference (a set of four major volumes) at the graduate student level, laid out by the most prominent, respected researchers in the general field of Cosmology. These volumes will be a comprehensive review of the most important concepts and current status in the field of Cosmology of the Universe, covering both theory and observation.One of the most exciting parts of the encyclopedia is that it will exist in both print and, more importantly, electronic forms, perhaps even with some level of interactivity with material such as expanded explanations, movie clips, dynamic pictures, examples of on-line computation, etc. The electronic version will also reflect constant updates of the material. It will be a truly unique publication, unlike anything any of us have seen or known of in existence today.This comprehensive encyclopedia is edited by Dr. Giovanni Fazio from Harvard Smithsonian Center for Astrophysics, with an advisory board comprised of renowned scientists: Lars Hernquist and Abraham Loeb (Harvard Smithsonian Center for Astrophysics), and Christopher McKee (UC Berkeley). Each volume is authored/edited by a specialist in the area: Galaxy Formation and Evolution written by Rennan Barkana (Tel Aviv University), Numerical Simulations in Cosmology edited by Kentaro Nagamine (Osaka University / University of Nevada), Dark Energy written by Shinji Tsujikawa (Tokyo University of Science), and Dark Matter written by Jihn Kim (Seoul National University).
Download or read book Neutrino Astronomy Current Status Future Prospects written by Thomas K Gaisser and published by World Scientific. This book was released on 2017-03-20 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: This review volume is motivated by the recent discovery of high-energy astrophysical neutrinos by IceCube. The aim of the book is to bring together chapters on the status of current and future neutrino observatories with chapters on the implications and possible interpretations of the present observations and their upper limits. Each chapter is a mini-review of one aspect of the subject by leading experts. Taken together, the chapters constitute an up-to-date review of high-energy astrophysical neutrinos and their potential sources.
