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The rise of the cosmic ray positron fraction with energy, as first observed with high confidence by PAMELA, implies that a large flux of high energy positrons has been recently (or is being currently) injected into the local volume of the…

High Energy Astrophysical Phenomena · Physics 2013-08-13 Ilias Cholis , Dan Hooper

The multi-component decaying dark matter (DM) scenario is investigated to explain the possible excesses in the positron fraction by PAMELA and recently confirmed by AMS-02, and in the total $e^+ +e^-$ flux observed by Fermi-LAT. By…

High Energy Physics - Phenomenology · Physics 2014-04-02 Chao-Qiang Geng , Da Huang , Lu-Hsing Tsai

The positron fraction in cosmic rays was found to be a 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 2015-02-25 M. Boudaud , S. Aupetit , S. Caroff , A. Putze , G. Belanger , Y. Genolini , C. Goy , V. Poireau , V. Poulin , S. Rosier , P. Salati , L. Tao , M. Vecchi

The Fermi-LAT \gamma-ray data have been used to study the morphological and spectral features of the so-called GeV excess - a diffuse radiation component recently discovered towards the Galactic centre. We used the likelihood method to…

High Energy Astrophysical Phenomena · Physics 2016-04-27 Rui-zhi Yang , Felix Aharonian

The first published Fermi large area telescope (Fermi-LAT) measurement of the isotropic diffuse gamma-ray emission is in good agreement with a single power law, and is not showing any signature of a dominant contribution from dark matter…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 LAT collaboration , A. A. Abdo , M. Ackermann , M. Ajello , L. Baldini , J. Ballet , G. Barbiellini , D. Bastieri , K. Bechtol , R. Bellazzini , B. Berenji , R. D. Blandford , E. D. Bloom , E. Bonamente , A. W. Borgland , A. Bouvier , J. Bregeon , A. Brez , M. Brigida , P. Bruel , T. H. Burnett , S. Buson , G. A. Caliandro , R. A. Cameron , P. A. Caraveo , S. Carrigan , J. M. Casandjian , C. Cecchi , O. C. Elik , A. Chekhtman , C. C. Cheung , J. Chiang , S. Ciprini , R. Claus , J. Cohen-Tanugi , J. Conrad , S. Cutini , C. D. Dermer , A. de Angelis , F. de Palma , S. W. Digel , E. do Couto e Silva , P. S. Drell , R. Dubois , D. Dumora , Y. Edmonds , C. Farnier , C. Favuzzi , S. J. Fegan , W. B. Focke , P. Fortin , M. Frailis , Y. Fukazawa , P. Fusco , F. Gargano , D. Gasparrini , N. Gehrels , S. Germani , N. Giglietto , F. Giordano , T. Glanzman , G. Godfrey , J. E. Grove , L. Guillemot , S. Guiriec , M. Gustafsson , D. Hadasch , A. K. Harding , D. Horan , R. E. Hughes , A. S. Johnson , W. N. Johnson , T. Kamae , H. Katagiri , J. Kataoka , N. Kawai , M. Kerr , J. Knodlseder , M. Kuss , J. Lande , L. Latronico , M. Llena Garde , F. Longo , F. Loparco , B. Lott , M. N. Lovellette , P. Lubrano , A. Makeev , M. N. Mazziotta , J. E. McEnery , C. Meurer , P. F. Michelson , W. Mitthumsiri , T. Mizuno , C. Monte , M. E. Monzani , A. Morselli , I. V. Moskalenko , S. Murgia , P. L. Nolan , J. P. Norris , E. Nuss , T. Ohsugi , N. Omodei , E. Orlando , J. F. Ormes , D. Paneque , J. H. Panetta , D. Parent , V. Pelassa , M. Pepe , M. Pesce-Rollins , F. Piron , S. Raino , R. Rando , A. Reimer , O. Reimer , T. Reposeur , A. Y. Rodriguez , M. Roth , H. F. W. Sadrozinski , A. Sander , P. M. Saz Parkinson , J. D. Scargle , A. Sellerholm , C. Sgro , E. J. Siskind , P. D. Smith , G. Spandre , P. Spinelli , J. L. Starck , M. S. Strickman , D. J. Suson , H. Takahashi , T. Tanaka , J. B. Thayer , J. G. Thayer , D. F. Torres , Y. Uchiyama , T. L. Usher , V. Vasileiou , N. Vilchez , V. Vitale , A. P. Waite , P. Wang , B. L. Winer , K. S. Wood , T. Ylinen , G. Zaharijas , M. Ziegle

Dark Matter annihilation (DMA) may yield an excess of gamma rays and antimatter particles, like antiprotons and positrons, above the background from cosmic ray interactions. The excess of diffuse Galactic Gamma Rays from EGRET shows all the…

High Energy Physics - Phenomenology · Physics 2015-05-13 W. de Boer

Pulsars are believed to be sources of relativistic electrons and positrons. The abundance of detections of gamma-ray millisecond pulsars by Fermi Large Area Telescope coupled with their light curve characteristics that imply copious pair…

High Energy Astrophysical Phenomena · Physics 2015-06-23 C. Venter , A. Kopp , P. L. Gonthier , A. K. Harding , I. Büsching

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

High Energy Astrophysical Phenomena · Physics 2009-06-19 LAT Collaboration

The high-quality Fermi LAT observations of gamma-ray pulsars have opened a new window to understanding the generation mechanisms of high-energy emission from these systems. The high statistics allow for careful modeling of the light curve…

High Energy Astrophysical Phenomena · Physics 2011-11-03 Megan E. DeCesar , Alice K. Harding , M. Coleman Miller , Ioannis Contopoulos , Constantinos Kalapotharakos , Damien Parent

We analyze the contribution of gamma-ray pulsars from the first Fermi-Large Area Telescope (LAT) catalogue to the local flux of cosmic-ray electrons and positrons (e+e-). We present new distance estimates for all Fermi gamma-ray pulsars,…

High Energy Astrophysical Phenomena · Physics 2010-02-15 Leo Gendelev , Stefano Profumo , Michael Dormody

The rapid rise in the cosmic ray positron fraction above 10 GeV, as measured by PAMELA and AMS, suggests the existence of nearby primary sources of high energy positrons, such as pulsars or annihilating/decaying dark matter. In contrast,…

High Energy Astrophysical Phenomena · Physics 2014-03-05 Ilias Cholis , Dan Hooper

The latest results from PAMELA and FERMI experiments confirm the necessity to improve theoretical models of production and propagation of galactic electrons and positrons. There are many possible explanations for the positron excess…

High Energy Astrophysical Phenomena · Physics 2012-05-04 Roberto A. Lineros

A precision measurement by AMS-02 of the positron fraction in primary cosmic rays is presented on this proceeding. Over the last two decades, there has been a strong interest in the cosmic ray positron fraction which exhibit an excess of…

High Energy Astrophysical Phenomena · Physics 2017-01-02 Sami Caroff

We are constructing a model which aims to reproduce observational data of many kinds related to cosmic-ray origin and propagation: direct measurements of nuclei, antiprotons, electrons and positrons, gamma-rays, and synchrotron radiation.…

Astrophysics · Physics 2007-05-23 A. W. Strong , I. V. Moskalenko

Recent observations by PAMELA, Fermi-LAT, and AMS-02 have conclusively indicated a rise in the cosmic-ray positron fraction above 10 GeV, a feature which is impossible to mimic under the paradigm of secondary positron production with…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Tim Linden , Stefano Profumo

A measurement of the cosmic ray positron fraction e+/(e+ + e-) in the energy range of 1-30 GeV is presented. The measurement is based on data taken by the AMS-01 experiment during its 10 day Space Shuttle flight in June 1998. A proton…

Astrophysics · Physics 2008-11-26 01 Collaboration

Motivated by the anomalous positron flux recently reported by the PAMELA collaboration, we study the cosmic-ray positron produced by the pair annihilation and the decay of superparticle dark matter. We calculate the cosmic-ray positron flux…

High Energy Physics - Phenomenology · Physics 2015-05-13 Koji Ishiwata , Shigeki Matsumoto , Takeo Moroi

Precision measurements by the Alpha Magnetic Spectrometer (AMS-02) on the International Space Station of the primary cosmic-ray electron flux and the positron flux will be discussed. The electron flux and the positron flux each require a…

High Energy Astrophysical Phenomena · Physics 2017-01-26 Maura Graziani

The direct measurements of electrons and positrons over the last 30 years, corrected for the solar effect in the force-field approximation, are considered. The resulting overall electron spectrum may be fitted with a single power law above…

Astrophysics · Physics 2011-08-19 Diego Casadei , Veronica Bindi

Interstellar synchrotron emission depends on Galactic magnetic fields and on cosmic-ray leptons. Observations of radio emission are an important tool for studying cosmic-ray propagation models and interstellar electron spectrum and…

Astrophysics of Galaxies · Physics 2013-07-24 Elena Orlando , Andrew W. Strong