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Very recently, PAMELA Collaboration has formally reported two sets of data on positron and antiproton flux measurements done at very high energies and with unprecedented accuracy. The reports reveal a puzzle of great topical interest and…

High Energy Astrophysical Phenomena · Physics 2009-07-17 Goutam Sau , S. K. Biswas , S. Bhattacharyya

The $\gamma$-ray emission from stars is induced by the interaction of cosmic rays with stellar atmospheres and photon fields. This emission is expected to come in two components: a stellar disk emission, where $\gamma$-rays are mainly…

High Energy Astrophysical Phenomena · Physics 2021-08-04 Raniere de Menezes , Elena Orlando , Mattia Di Mauro , Andrew Strong

Recent observations of lepton cosmic rays, coming from the PAMELA and FERMI experiments, have pushed our understanding of the interstellar medium and cosmic rays sources to unprecedented levels. The imprint of dark matter on lepton cosmic…

High Energy Astrophysical Phenomena · Physics 2011-01-27 Roberto A. Lineros

Astrophysical and cosmological observations do not require the dark matter particles to be absolutely stable. If they are indeed unstable, their decay into positrons might occur at a sufficiently large rate to allow the indirect detection…

High Energy Physics - Phenomenology · Physics 2011-05-05 Alejandro Ibarra , David Tran

We analyse recently measured nonlinear photoemission spectra from Ag surfaces that reveal resonances whose energies do not scale with the applied photon energy but stay pinned to multiples of bulk plasmon energy $\hbar\omega_p$ above the…

Materials Science · Physics 2021-05-05 Dino Novko , Vito Despoja , Marcel Reutzel , Andi Li , Hrvoje Petek , Branko Gumhalter

Several cosmic ray experiments have measured the positron fraction up to few hundred GeV. Their data have revealed an excess of positrons above 10 GeV that is not consistent with the secondary production of these particles in the…

High Energy Astrophysical Phenomena · Physics 2013-07-22 S. Della Torre , M. Gervasi , P. G. Rancoita , D. Rozza , A. Treves

The Fermi Large Area Telescope (LAT) data have confirmed the pulsed emission from all six high-confidence gamma-ray pulsars previously known from the EGRET observations. We report results obtained from the analysis of 13 months of LAT data…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Fermi LAT Collaboration , A. A. Abdo

Most of the diffuse Galactic GeV gamma-ray emission is produced via collisions of cosmic ray (CR) protons with ISM protons. As such the observed spectra of the gamma-rays and the CRs should be strongly linked. Recent observations of…

High Energy Astrophysical Phenomena · Physics 2017-02-01 Lara Nava , David Benyamin , Tsvi Piran , Nir J. Shaviv

We consider the problem of the cosmic ray spectrum formation assuming that cosmic rays are produced by Galactic sources. The anomalous diffusion equation proposed in our recent papers is used to describe cosmic ray propagation in the…

High Energy Astrophysical Phenomena · Physics 2019-05-17 Nikolay Volkov , Anatoly Lagutin , Alexander Tyumentsev , Roman Raikin

In over two years of operation Fermi-LAT has revolutionized our knowledge of the gamma-ray sky. Interstellar gamma rays are part of this new era and allow unprecedented tests for models of cosmic rays in the Galaxy. The extension to lower…

High Energy Astrophysical Phenomena · Physics 2017-08-23 A. W. Strong

The Large Area Telescope onboard the Fermi Gamma-ray Space Telescope has collected the largest ever sample of high-energy cosmic-ray electron and positron events. Possible features in their energy spectrum could be a signature of the…

High Energy Astrophysical Phenomena · Physics 2018-07-13 M. N. Mazziotta , F. Costanza , A. Cuoco , F. Gargano , F. Loparco , S. Zimmer

We argue that we may be able to sort out dark matter models in which electrons are generated through the annihilation and/or decay of dark matter, by using a fact that the initial energy spectrum is reflected in the cosmic-ray electron flux…

We study the capabilities of the Fermi-LAT instrument for identifying particle Dark Matter properties as mass, annihilation cross section and annihilation channels, with gamma-ray observations from the Galactic Center. For the potential…

High Energy Astrophysical Phenomena · Physics 2010-12-02 Nicolas Bernal

We report on the \textit{Fermi}-LAT observations of the Geminga pulsar, the second brightest non-variable GeV source in the $\gamma$-ray sky and the first example of a radio-quiet $\gamma$-ray pulsar. The observations cover one year, from…

High Energy Astrophysical Phenomena · Physics 2016-04-13 LAT Collaboration , A. A. Abdo

Supernova remnants have long been regarded as sources of the Galactic cosmic rays up to petaelectronvolts, but convincing evidence is still lacking. In this work we explore the common origin of the subtle features of the cosmic ray spectra,…

High Energy Astrophysical Phenomena · Physics 2009-07-17 Hong-Bo Hu , Qiang Yuan , Bo Wang , Chao Fan , Jian-Li Zhang , Xiao-Jun Bi

We study the possibility that the gamma ray emission in the Fermi bubbles observed is produced by cosmic ray electrons with a spectrum similar to Galactic cosmic rays. We argue that the cosmic ray electrons steepen near 1 TeV from $E^{-3}$…

High Energy Astrophysical Phenomena · Physics 2013-09-16 Nayantara Gupta , Biman B. Nath , Peter L. Biermann , Eun -Suk Seo , Todor Stanev , Julia Becker Tjus

The cosmic-ray fluxes of electrons and positrons ($e^{\pm}$) are measured with high precision by the space-borne particle spectrometer AMS-02. To infer a precise interpretation of the production processes for $e^{\pm}$ in our Galaxy, it is…

High Energy Astrophysical Phenomena · Physics 2022-07-05 Luca Orusa , Mattia Di Mauro , Fiorenza Donato , Michael Korsmeier

Taking into account spins, we classify all two-body non-relativistic Dark Matter annihilation channels to the allowed polarization states of Standard Model particles, computing the energy spectra of the stable final-state particles relevant…

High Energy Physics - Phenomenology · Physics 2013-10-07 Marco Cirelli , Mario Kadastik , Martti Raidal , Alessandro Strumia

Morphologically it appears as if the Vela X PWN consists of two emission regions: whereas X-ray (1 keV) and very high energy (VHE) H.E.S.S. gamma-ray observations appear to define a cocoon type shape south of the pulsar, radio observations…

Astrophysics · Physics 2009-11-13 O. C. de Jager , P. O. Slane , S. LaMassa

There is evidence for a spectral line at $E_\gamma\approx 130$ GeV in the Fermi-LAT data that can be explained as dark mater particles annihilating into photons. We review a well known dark matter model that consists in a singlet Dirac…

High Energy Physics - Phenomenology · Physics 2014-10-13 T. H. Franarin , C. A. Z. Vasconcellos , D. Hadjimichef