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The rise in the cosmic-ray positron fraction measured by the PAMELA satellite is likely due to the presence of astrophysical sources of positrons, e.g. pulsars, on the kpc scale around the Earth. Nevertheless, assessing the properties of…

High Energy Astrophysical Phenomena · Physics 2011-07-19 Julien Lavalle

One of the major results from the study of gamma-ray bursts with the Fermi Gamma-ray Space Telescope has been the confirmation that several emission components can be present in the energy spectrum. Here we reanalyse the spectrum of GRB…

High Energy Astrophysical Phenomena · Physics 2016-03-23 Elena Moretti , Magnus Axelsson

The PAMELA satellite has observed an excess in the positron to electron ratio above theoretical predictions in the range 10 - 100 GeV that increases with energy. We propose that the excess is not due to a change in the local interstellar…

High Energy Astrophysical Phenomena · Physics 2012-11-06 J. P. Roberts

The Fermi Bubbles are gamma-ray structures extending from the center of the Milky Way to +/-50 degree Galactic latitude that were discovered in data obtained by the Fermi/LAT instrument. Their origin and power source remain uncertain. To…

High Energy Astrophysical Phenomena · Physics 2025-11-11 Ami Tank , Roland Crocker , Mark R. Krumholz

Recent precision measurements of the flux of cosmic ray positrons by the Alpha Magnetic Spectrometer show that the spectrum has a marked softening feature for energies close to one TeV. A possible interpretation of this result is that the…

High Energy Astrophysical Phenomena · Physics 2019-02-19 Paolo Lipari

In eight years of operation, the Fermi Large Area Telescope (LAT) has detected a large sample of cosmic-ray protons. The LAT's wide field of view and full-sky coverage make it an excellent instrument for studying anisotropy in the arrival…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Matthew Meehan , Justin Vandenbroucke

The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of the emission towards the Galactic centre (GC) in high-energy gamma-rays. This paper describes the analysis of data taken during the first 62 months of the…

High Energy Astrophysical Phenomena · Physics 2017-02-22 LAT Collaboration

The recent solar minimum activity period and the consequent minimum modulation conditions for cosmic rays were unusual compared to previous solar minimum periods. The highest spectra of galactic protons (and other cosmic rays) were recorded…

Solar and Stellar Astrophysics · Physics 2013-08-08 M. S. Potgieter , R. Du T. Strauss , N. De Simone , M. Boezio

We report the detection of the lunar gamma-ray emission during the first year of Fermi-LAT observations. Such emission is produced by cosmic ray nuclei interacting with the lunar surface. Thanks to the solar minimum conditions and the…

High Energy Astrophysical Phenomena · Physics 2019-08-15 N. Giglietto

The ISS-based CALET (CALorimetric Electron Telescope) detector can play an important role in indirect search for Dark Matter (DM), measuring the electron+positron flux in the TeV region for the first time directly. With its fine energy…

High Energy Astrophysical Phenomena · Physics 2017-08-11 S. Bhattacharyya , H. Motz , S. Torii , Y. Asaoka

{\it Fermi} satellite has detected extra spectral components in GeV energy range in several GRBs. Those components have power-law shapes, which may contribute to also X-ray band. The limited photon statistics make it difficult to determine…

High Energy Astrophysical Phenomena · Physics 2011-11-02 Katsuaki Asano , Peter Mészáros , Kohta Murase , Susumu Inoue , Toshio Terasawa

A new calculation of the Galactic diffuse gamma-ray spectrum from the decay of secondary particles produced by interactions of cosmic-ray protons with interstellar matter is presented. The calculation utilizes the modern Monte Carlo event…

Astrophysics · Physics 2009-10-28 Masaki Mori

We report the detection of gamma-ray emission from PWN Kes 75 and PSR J1846-0258. Through modeling the spectral energy distribution incorporating the new Fermi-LAT data, we find the the observed gamma-ray emission is likely a combination of…

High Energy Astrophysical Phenomena · Physics 2023-02-01 Samayra M. Straal , Joseph D. Gelfand , Jordan L. Eagle

It is well known that the dark matter dominates the dynamics of galaxies and clusters of galaxies. Its constituents remain a mystery despite an assiduous search for them over the past three decades. Recent results from the satellite-based…

High Energy Astrophysical Phenomena · Physics 2011-06-07 Debtosh Chowdhury , Chanda J. Jog , Sudhir K Vempati

The positron fraction in cosmic rays was found to be steadily increasing in function of energy, above $\sim$10 GeV. This behaviour contradicts standard astrophysical mechanisms, in which positrons are secondary particles, produced in the…

High Energy Astrophysical Phenomena · Physics 2015-10-27 Mathieu Boudaud

Designed as a high-sensitivity gamma-ray observatory, the Fermi Large Area Telescope is also an electron detector with a large acceptance exceeding 2 sq-mt sr at 300 GeV. Building on the gamma-ray analysis, we have developed an efficient…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Luca Latronico

The Fermi-LAT collaboration recently confirmed a discrepancy between the observed longitudinal profile of gamma-ray diffuse emission from the Galaxy and that computed with numerical codes assuming that Cosmic Rays (CRs) are produced by…

High Energy Astrophysical Phenomena · Physics 2013-07-01 Daniele Gaggero , Carmelo Evoli , Dario Grasso , Luca Maccione

Supernova remnants (SNRs) have been regarded for many decades as the sources of Galactic cosmic rays (CRs) up to a few PeV. However, only with the advent of Fermi-LAT it has been possible to detect - at least in some SNRs - \gamma-rays…

High Energy Astrophysical Phenomena · Physics 2013-03-12 Damiano Caprioli

We perform two distinct spatio-spectral reconstructions of the gamma-ray sky in the range of 0.56-316 GeV based on Fermi Large Area Telescope (LAT) data. Both describe the sky brightness to be composed of a diffuse-emission and a…

High Energy Astrophysical Phenomena · Physics 2023-12-13 Lukas I. Platz , Jakob Knollmüller , Philipp Arras , Philipp Frank , Martin Reinecke , Dominik Jüstel , Torsten A. Enßlin

Cosmic rays interacting with gas and photon fields in the Galaxy produce interstellar gamma-ray emission (IGE), which accounts for almost 50% of the photons detected at gamma-ray energies. Models of this IGE have to be very accurate for…

High Energy Astrophysical Phenomena · Physics 2019-02-28 E. Orlando
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