TeV gamma rays from blazars beyond z= 1?
... by the integrated light of resolved galaxies. Recent phenomenological and theoretical studies (e.g., Refs. [2, 3]) also favor the models of EBL which are close to the limit derived from the galaxy counts (for a recent review see Ref. [4]). This implies that further decrease in the level EBL is pract ...
... by the integrated light of resolved galaxies. Recent phenomenological and theoretical studies (e.g., Refs. [2, 3]) also favor the models of EBL which are close to the limit derived from the galaxy counts (for a recent review see Ref. [4]). This implies that further decrease in the level EBL is pract ...
Analysis of the Large Gamma Ray Flares of Mkn 421
... First, I wish to sincerely thank my supervisors Dr. Manel Martinez from the Institut de Fisica d’Altes Energies/Spain and Dr. Eckart Lorenz from the Max Planck Institut für Physik in Munich for supervising and providing me with this interesting Ph.D. subject and for giving me a chance to do real phy ...
... First, I wish to sincerely thank my supervisors Dr. Manel Martinez from the Institut de Fisica d’Altes Energies/Spain and Dr. Eckart Lorenz from the Max Planck Institut für Physik in Munich for supervising and providing me with this interesting Ph.D. subject and for giving me a chance to do real phy ...
Gamma-ray absorption and pair echos at very high
... to produce electron-positron pairs (γ +γ → e+ +e− ), as long as there is sufficient opacity for energies satisfying the threshold condition Eϵ(1−cos θ) ≥ 2m2e c4 , where θ is the incidence angle of the two photons. The observed spectra of the gamma-ray sources should then exbihit corresponding attenu ...
... to produce electron-positron pairs (γ +γ → e+ +e− ), as long as there is sufficient opacity for energies satisfying the threshold condition Eϵ(1−cos θ) ≥ 2m2e c4 , where θ is the incidence angle of the two photons. The observed spectra of the gamma-ray sources should then exbihit corresponding attenu ...
doc - SAUND Main Page
... challenging fields of modern physics. While abundant high quality data are routinely collected up to energies of several tens of GeV, the study of higher energies is limited by the very low fluxes available. Yet the region around 1020 eV should be particularly interesting since on one hand we do not ...
... challenging fields of modern physics. While abundant high quality data are routinely collected up to energies of several tens of GeV, the study of higher energies is limited by the very low fluxes available. Yet the region around 1020 eV should be particularly interesting since on one hand we do not ...
History of the 2.7 K Temperature Prior to Penzias and Wilson
... In a region of space not in the neighbourhood of any star this constitutes the whole field of radiation, and a black body, e. g. a black bulb thermometer, will there take up a temperature of 3º.18 so that its emission may balance the radiation falling on it and absorbed by it. This is sometimes call ...
... In a region of space not in the neighbourhood of any star this constitutes the whole field of radiation, and a black body, e. g. a black bulb thermometer, will there take up a temperature of 3º.18 so that its emission may balance the radiation falling on it and absorbed by it. This is sometimes call ...
The depth of maximum shower development and its fluctuations
... from the array center (Petrov et al., 2008). Examples demonstrating these techniques for xmax estimation are shown in Figs. 1 and 2. The sensitivity of these techniques is described in works (Dyakonov et al., 1991; Belyaev et al., 1980; Dyakonov, 1981; Hillas and Patterson, 1983). There are various ...
... from the array center (Petrov et al., 2008). Examples demonstrating these techniques for xmax estimation are shown in Figs. 1 and 2. The sensitivity of these techniques is described in works (Dyakonov et al., 1991; Belyaev et al., 1980; Dyakonov, 1981; Hillas and Patterson, 1983). There are various ...
cosmic ray transport and production in the galaxy: a
... because the stochastic differential equations are like first-order differential equations (see, e.g., Zhang 1999). It is particularly advantageous for high-dimensional problems, because adding an additional dimension typically entails adding just one line of additional computer code with little incr ...
... because the stochastic differential equations are like first-order differential equations (see, e.g., Zhang 1999). It is particularly advantageous for high-dimensional problems, because adding an additional dimension typically entails adding just one line of additional computer code with little incr ...
ppt - Leeds Astrophysics
... • Mono: wider energy range (1017.4 < E < 1020.5 eV), best statistics. • Stereo: best reconstruction, covers 1018.5 < E < 1020.5 eV. • In this energy range expect to see: – Transition from galactic to extragalactic sources via transition from heavy to light composition. – Two spectral features due to ...
... • Mono: wider energy range (1017.4 < E < 1020.5 eV), best statistics. • Stereo: best reconstruction, covers 1018.5 < E < 1020.5 eV. • In this energy range expect to see: – Transition from galactic to extragalactic sources via transition from heavy to light composition. – Two spectral features due to ...
Microsoft Word Format - University of Toronto Physics
... result. Setting up and testing the necessary data taking electronics is an important part of the experiment. Cosmic Ray and Muon Physics Cosmic rays, discovered in the 1930's as background radiation in laboratory experiments, provide us with a free source of muons. The flux of muons is not difficult ...
... result. Setting up and testing the necessary data taking electronics is an important part of the experiment. Cosmic Ray and Muon Physics Cosmic rays, discovered in the 1930's as background radiation in laboratory experiments, provide us with a free source of muons. The flux of muons is not difficult ...
High energy universe – Satellite missions
... in plasmas of temperatures larger than millions of degree Kelvin. At these temperatures, hydrogen and helium are fully ionized. Heavier elements are stripped off most of their electrons except perhaps the inner K or L shell electrons. They produce high energy line emission such as the well identifie ...
... in plasmas of temperatures larger than millions of degree Kelvin. At these temperatures, hydrogen and helium are fully ionized. Heavier elements are stripped off most of their electrons except perhaps the inner K or L shell electrons. They produce high energy line emission such as the well identifie ...
Diffusive shock acceleration
... Cosmic rays are energetic particles. Primary: - protons and heavier nuclei - electrons (and positrons) Secondary CR include also: - antiprotons, positrons, neutrinos, gamma rays with energies much above the thermal plasma and the non-thermal energy distribution. In our Galaxy: ...
... Cosmic rays are energetic particles. Primary: - protons and heavier nuclei - electrons (and positrons) Secondary CR include also: - antiprotons, positrons, neutrinos, gamma rays with energies much above the thermal plasma and the non-thermal energy distribution. In our Galaxy: ...
Ionization in atmospheres of Brown Dwarfs and extrasolar planets IV
... effect of a weak magnetic field (B < 1 mG) on the cosmic ray spectrum. The models of Velinov & Mateev (2008); Velinov et al. (2009) have been tested against various atmospheric profiles and model assumptions (Mishev & Velinov 2008, 2010). Padovani et al. (2009) numerically solve the propagation inte ...
... effect of a weak magnetic field (B < 1 mG) on the cosmic ray spectrum. The models of Velinov & Mateev (2008); Velinov et al. (2009) have been tested against various atmospheric profiles and model assumptions (Mishev & Velinov 2008, 2010). Padovani et al. (2009) numerically solve the propagation inte ...
Electron/proton separation and analysis techniques used in the AMS
... AMS-02 is a large acceptance cosmic ray detector which has been installed on the International Space Station (ISS) in May 2011, where it is collecting cosmic rays up to TeV energies. The search for Dark Matter indirect signatures in the rare components of the cosmic ray fluxes is among the main obje ...
... AMS-02 is a large acceptance cosmic ray detector which has been installed on the International Space Station (ISS) in May 2011, where it is collecting cosmic rays up to TeV energies. The search for Dark Matter indirect signatures in the rare components of the cosmic ray fluxes is among the main obje ...
The PAMELA Space Experiment
... questions of cosmic ray physics, from particle production and propagation in the galaxy to charge dependent modulation in the heliosphere to dark matter detection. 1) Antiprotons: PAMELA detectable energy spectrum of p ranges from 80 MeV to 190 GeV. Although the quality of p data has been improving ...
... questions of cosmic ray physics, from particle production and propagation in the galaxy to charge dependent modulation in the heliosphere to dark matter detection. 1) Antiprotons: PAMELA detectable energy spectrum of p ranges from 80 MeV to 190 GeV. Although the quality of p data has been improving ...
The Cosmic Rays and Our Galaxy
... effect” and rejected the Millikan theory. In 1938–1939 (in Paris first and then in the Alps mountains), P. Auger and collaborators showed that groups of particles could arrive in time coincidence on detectors separated by distances as large as 200 m. This was the first indication that the observed p ...
... effect” and rejected the Millikan theory. In 1938–1939 (in Paris first and then in the Alps mountains), P. Auger and collaborators showed that groups of particles could arrive in time coincidence on detectors separated by distances as large as 200 m. This was the first indication that the observed p ...
press release - University of Michigan
... one of the most compelling enigmas of modern science--what is the universe made of?-told by one of today's foremost pioneers in the study of dark matter. Blending cutting-edge science with her own behind-the-scenes insights as a leading researcher in the field, acclaimed theoretical physicist Kather ...
... one of the most compelling enigmas of modern science--what is the universe made of?-told by one of today's foremost pioneers in the study of dark matter. Blending cutting-edge science with her own behind-the-scenes insights as a leading researcher in the field, acclaimed theoretical physicist Kather ...
High Energy Gamma Rays from Protons Hitting
... paper [3]. As it happens an excess of 511 keV annihilation radiation from positrons has been observed coming from the general vicinity of the center of our galaxy[10,, 11, 16], and to date there is no generally accepted conventional explanation for the origin these positrons. The absence of in-fligh ...
... paper [3]. As it happens an excess of 511 keV annihilation radiation from positrons has been observed coming from the general vicinity of the center of our galaxy[10,, 11, 16], and to date there is no generally accepted conventional explanation for the origin these positrons. The absence of in-fligh ...
EXCESS NEGATIVE CHARGE OF AN ELECTRON-PHOTON
... We investigate the excess of electrons in an electron-photon shower. This excess is caused by annihilation of the positrons in flight and by the Compton and o -electrons in the cascade. It is shown that at the maximum of the shower the excess may comprise ten percent of the total number of shower pa ...
... We investigate the excess of electrons in an electron-photon shower. This excess is caused by annihilation of the positrons in flight and by the Compton and o -electrons in the cascade. It is shown that at the maximum of the shower the excess may comprise ten percent of the total number of shower pa ...
8 Seeing the Heavens: Telescopes and Detectors
... 8.5 Non-Electromagnetic Observations Most, but not all, of our information in astronomy comes from detecting electromagnetic waves. Important examples of non-electromagnetic data include 1. Cosmic rays 2. Neutrinos 3. Gravitational waves ...
... 8.5 Non-Electromagnetic Observations Most, but not all, of our information in astronomy comes from detecting electromagnetic waves. Important examples of non-electromagnetic data include 1. Cosmic rays 2. Neutrinos 3. Gravitational waves ...
Invited Talks at Major Meetings Andreas Albrecht Updated 8/31
... Dialogues in Cosmology: Princeton 250th Anniversary conference, Princeton, June ...
... Dialogues in Cosmology: Princeton 250th Anniversary conference, Princeton, June ...
Shell supernova remnants as cosmic accelerators: I Stephen Reynolds, North Carolina State University
... Spectrum: same slope as synchrotron as long as hi ≪ mec2; then KleinNishina corrections reduce crosssection, steepen spectrum Usually, local optical/IR radiation field is less important than upscattering cosmic microwave background photons: ICCMB ...
... Spectrum: same slope as synchrotron as long as hi ≪ mec2; then KleinNishina corrections reduce crosssection, steepen spectrum Usually, local optical/IR radiation field is less important than upscattering cosmic microwave background photons: ICCMB ...
Cosmic ray
Cosmic rays are immensely high-energy radiation, mainly originating outside the Solar System. They may produce showers of secondary particles that penetrate and impact the Earth's atmosphere and sometimes even reach the surface. Composed primarily of high-energy protons and atomic nuclei, they are of mysterious origin. Data from the Fermi space telescope (2013) has been interpreted as evidence that a significant fraction of primary cosmic rays originate from the supernovae of massive stars. However, this is not thought to be their only source. Active galactic nuclei probably also produce cosmic rays.The term ray is a historical accident, as cosmic rays were at first, and wrongly, thought to be mostly electromagnetic radiation. In common scientific usage high-energy particles with intrinsic mass are known as ""cosmic"" rays, and photons, which are quanta of electromagnetic radiation (and so have no intrinsic mass) are known by their common names, such as ""gamma rays"" or ""X-rays"", depending on their origin.Cosmic rays attract great interest practically, due to the damage they inflict on microelectronics and life outside the protection of an atmosphere and magnetic field, and scientifically, because the energies of the most energetic ultra-high-energy cosmic rays (UHECRs) have been observed to approach 3 × 1020 eV, about 40 million times the energy of particles accelerated by the Large Hadron Collider. One can show that such enormous energies might be achieved by means of the Centrifugal mechanism of acceleration in Active galactic nuclei. At 50 J, the highest-energy ultra-high-energy cosmic rays have energies comparable to the kinetic energy of a 90-kilometre-per-hour (56 mph) baseball. As a result of these discoveries, there has been interest in investigating cosmic rays of even greater energies. Most cosmic rays, however, do not have such extreme energies; the energy distribution of cosmic rays peaks at 0.3 gigaelectronvolts (4.8×10−11 J).Of primary cosmic rays, which originate outside of Earth's atmosphere, about 99% are the nuclei (stripped of their electron shells) of well-known atoms, and about 1% are solitary electrons (similar to beta particles). Of the nuclei, about 90% are simple protons, i. e. hydrogen nuclei; 9% are alpha particles, and 1% are the nuclei of heavier elements, called HZE ions. A very small fraction are stable particles of antimatter, such as positrons or antiprotons. The precise nature of this remaining fraction is an area of active research. An active search from Earth orbit for anti-alpha particles has failed to detect them.