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Author: Aous Abdo Publisher: ISBN: 9783836486767 Category : Science Languages : en Pages : 240
Book Description
Very high energy gamma-rays can be used to probe some of the most violent environments in the Universe, such as supernovae and supernovae remnants, pulsar-powered nebulae, and superluminal jets of active galaxies powered by super-massive black holes. The diffuse gamma radiation arising from the interaction of cosmic-ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of cosmic-rays, whose origin is still a mystery a century after their discovery. Unlike charged cosmic-ray particles, gamma-ray photons are not bent in galactic and extra-galactic magnetic fields. They are also less easily absorbed by gas and dust in galaxies than light of longer wavelengths. Since there are very few of these photons, detection is done using ground instruments with large sensitive area. The main challenge for such instruments is to distinguish gamma-ray photons from the overwhelming background of hadronic cosmic rays. In this book, a new background rejection technique for the Milagro detector is presented. This new technique resulted in the discovery of three new VHE gamma-ray sources along with diffuse emission of VHE gamma-rays from the Galaxy.
Author: Aous Abdo Publisher: ISBN: 9783836486767 Category : Science Languages : en Pages : 240
Book Description
Very high energy gamma-rays can be used to probe some of the most violent environments in the Universe, such as supernovae and supernovae remnants, pulsar-powered nebulae, and superluminal jets of active galaxies powered by super-massive black holes. The diffuse gamma radiation arising from the interaction of cosmic-ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of cosmic-rays, whose origin is still a mystery a century after their discovery. Unlike charged cosmic-ray particles, gamma-ray photons are not bent in galactic and extra-galactic magnetic fields. They are also less easily absorbed by gas and dust in galaxies than light of longer wavelengths. Since there are very few of these photons, detection is done using ground instruments with large sensitive area. The main challenge for such instruments is to distinguish gamma-ray photons from the overwhelming background of hadronic cosmic rays. In this book, a new background rejection technique for the Milagro detector is presented. This new technique resulted in the discovery of three new VHE gamma-ray sources along with diffuse emission of VHE gamma-rays from the Galaxy.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The diffuse gamma radiation arising from the interaction of cosmic ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of the cosmic rays. Milagro is a water Cherenkov detector that continuously views the entire overhead sky. The large field-of-view combined with the long observation time makes Milagro the most sensitive instrument available for the study of large, low surface brightness sources such as the diffuse gamma radiation arising from interactions of cosmic radiation with interstellar matter. In this paper we present spatial and flux measurements of TeV gamma-ray emission from the Cygnus Region. The TeV image shows at least one new source MGRO J2019+37 as well as correlations with the matter density in the region as would be expected from cosmic-ray proton interactions. However, the TeV gamma-ray flux as measured at (almost equal to)12 TeV from the Cygnus region (after excluding MGRO J2019+37) exceeds that predicted from a conventional model of cosmic ray production and propagation. This observation indicates the existence of either hard-spectrum cosmic-ray sources and/or other sources of TeV gamma rays in the region.
Author: Fegan David Publisher: World Scientific ISBN: 9813276878 Category : Science Languages : en Pages : 344
Book Description
This book documents how TeV gamma-ray astronomy painstakingly emerged from 20th century traditional cosmic-ray physics to become a keystone feature of contemporary high-energy astrophysics, fundamental to our understanding of high-energy cosmic processes and interactions. Contemporary TeV observations are based on the Imaging Atmospheric Cherenkov Technique and in excess of two hundred individual galactic and extra-galactic gamma-ray sources have now been discovered and studied in detail.The book tells the story from the perspective of the Whipple Observatory collaboration, pioneers of the imaging technique. At the same time, parallel developments by the broader community are constantly referenced, discussed and evaluated, mainly in the TeV energy regime but also where relevant at PeV energies. The narrative traces the contributions of many important participants active in the field since the mid-1950s and critically evaluates and provides commentary on the progress of research until the first sources were established beyond doubt, during the late 1980s and early 1990s. The final chapter presents a short summary of the contemporary status of TeV gamma-ray astronomy.Written predominantly from a historical perspective, the author guides readers through many decades of instrumental development and evolution, using only minimal mathematical background. This book will appeal to astrophysicists, particle physicists, traditional optical and radio astronomers, as well as others working across a variety of related cognate disciplines. It should be of interest and value to graduate students involved with contemporary fourth-generation TeV research programs such as CTA (Cherenkov Telescope Array).
Author: Heinrich J. Völk Publisher: Springer Science & Business Media ISBN: 9400901712 Category : Science Languages : en Pages : 447
Book Description
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.
Author: K.S. Cheng Publisher: Springer Science & Business Media ISBN: 1402022565 Category : Science Languages : en Pages : 412
Book Description
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: Nicole Firestone Publisher: ISBN: Category : Languages : en Pages :
Book Description
As neutrally-charged astrophysical messengers, gamma rays serve as powerful tools for determining the origins of incredibly high-energy particles from across our universe [1]. Gamma rays are considered to have the highest energy of all electromagnetic radiation, with energies spanning from 0.5 MeV to about 100 TeV [2]. Although lower-energy gamma rays can originate from within our solar system, gamma rays in the GeV and TeV ranges tend to originate from sources beyond our solar system [1]. By investigating these sources, we can understand more about the astrophysical phenomena that characterize the most extreme conditions in our universe, such as supernova remnants, gamma-ray bursts, and pulsars [3]. The High Altitude Water Cherenkov Gamma-Ray Observatory (HAWC) is one of the most sensitive gamma-ray detectors in the very high energy (VHE) regime, with the capability to observe gamma rays from 100 GeV and 100 TeV [4]. In 2017, HAWC conducted a blind search encompassing two thirds of the sky and 508 days of observations [4]. In this search, there were 16 VHE gamma-ray excesses that were unassociated with any previously discovered gamma-ray sources [4]. Now with data from 1523 days of observations, we begin to study these 16 unassociated candidate TeV sources in more detail. In this work, we update the locations of maximum significance for these candidate TeV sources and analyze the temporal progression of their significance and flux. This allows us to determine if they have faded into the diffuse gamma radiation or if they can still be considered unassociated candidate TeV sources. We then reevaluate the morphologies and spectral energy distributions of the remaining sources and discuss any recent observations from other gamma-ray observatories. We find that 10 of these 16 unassociated candidate TeV sources can still be considered candidate sources. In the future, we plan to use data from other observatories to continue to put better constrains on the morphology and spectral energy distributions for these sources and better understand their acceleration mechanisms. In addition, we plan to conduct a similar investigation with new HAWC excesses discovered with recent data from 1523 days of observations [5]. By investigating these excesses in the high-energy gamma-ray sky, we can discover and characterize new extreme astrophysical phenomena and ultimately uncover valuable information about the physical mechanisms that accelerate particles to very high energies.
Author: Aous Abdo
Author: Aous Abdo
Author: Aws Ahmad Abdo
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Author: 
Author: Fegan David
Author: Heinrich J. Völk
Author: John Joseph Quinn
Author: K.S. Cheng
Author: Nicole Firestone
Author: Sei Kato