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Excess microwave emission observed in the inner Galaxy (inner ~1 kpc) is consistent with synchrotron emission from highly relativistic electron-positron pairs produced by dark matter particle annihilation. More conventional sources for this…

Astrophysics · Physics 2008-04-08 Douglas P. Finkbeiner

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

Radioactive nuclei, especially those created in SN explosion, have long been suggested to be important contributors of galactic positrons. In this paper we describe the findings of three independent OSSE/SMM/TGRS studies of positron…

Astrophysics · Physics 2015-06-24 P. A. Milne , J. D. Kurfess , R. L. Kinzer , M. D. Leising

The bulk of the extragalactic background between 10 keV and 10 GeV is likely to be explained by the emission of Seyfert galaxies, type Ia supernovae, and blazars. However, as revealed by the INTEGRAL satellite, the bulge of our galaxy is an…

Indirect detection signals from dark matter annihilation are studied in the positron channel. We discuss in detail the positron propagation inside the galactic medium: we present novel solutions of the diffusion and propagation equations…

Astrophysics · Physics 2010-04-06 T. Delahaye , R. Lineros , F. Donato , N. Fornengo , P. Salati

The first detection of a gamma ray line with an energy of about 500 keV from the center our Galaxy dates back to the early seventies. Thanks to the astrophysical application of high spectral resolution detectors, it was soon clear that this…

High Energy Astrophysical Phenomena · Physics 2015-05-28 G. De Cesare

Positron annihilation radiation from the Galaxy has been observed by the OSSE, SMM and TGRS instruments. Improved spectral modeling of OSSE observations has allowed studies of the distribution of both positron annihilation radiation…

Astrophysics · Physics 2009-11-06 P. A. Milne , J. D. Kurfess , R. L. Kinzer , M. D. Leising

Indirect detection signals from dark matter annihilation are studied in the positron channel. We discuss in detail the positron propagation inside the galactic medium: we present novel solutions of the diffusion and propagation equations…

Astrophysics · Physics 2007-09-14 N. Fornengo , T. Delahaye , R. Lineros , F. Donato , P. Salati

We have obtained spectra of the Galactic center at energies 400-600 keV from high-resolution data acquired by the TGRS Ge spectrometer on board the WIND mission during 1995-1997. The data were obtained using an on-board occulter, and are…

Astrophysics · Physics 2009-10-30 M. J. Harris , B. J. Teegarden , T. L. Cline , N. Gehrels , D. M. Palmer , R. Ramaty , H. Seifert

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 large intensity of greater than 10 GeV positrons which apparently come from sources outside the Earth-Sun system observed recently by many spacecraft (PAMELA, FERMI, AMS2) is still a mystery with broad implications. In our attempts to…

Space Physics · Physics 2015-12-23 W. R. Webber

Diffuse gamma-ray line emission traces freshly produced radioisotopes in the interstellar gas, providing a unique perspective on the entire Galactic cycle of matter from nucleosynthesis in massive stars to their ejection and mixing in the…

In this paper we calculate the Galactic positron flux from dark matter annihilation in the frame of supersymmetry, taking the enhancement of the flux by existence of dark matter substructures into account. The propagation of positrons in…

Astrophysics · Physics 2010-10-27 Qiang Yuan , Xiao-Jun Bi

The small-scale distribution of dark matter in Galactic halos is poorly known. Several studies suggest that it could be very clumpy, which turns out to be of paramount importance when investigating the annihilation signal from exotic…

Astrophysics · Physics 2011-08-04 Julien Lavalle , Jonathan Pochon , Pierre Salati , Richard Taillet

Diffuse emission is often challenging since it is undetectable by most instruments, which are generally dedicated to point-source studies. The $^{26}$Al emission is a good illustration: the only available $^{26}$Al map to date has been…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Laurent Bouchet , Elisabeth Jourdain , Jean-Pierre Roques

In the Milky Way galaxy, positrons, which are responsible for the diffuse $511\,\mathrm{keV}$ gamma ray emission observed by space-based gamma ray observatories, are thought to annihilate predominantly through charge exchange interactions…

High Energy Astrophysical Phenomena · Physics 2018-08-15 Fiona H. Panther , Ivo R. Seitenzahl , Roland M. Crocker , Joshua R. Machacek , Dan J. Murtagh , Thomas Siegert , Roland Diehl

The Fermi-LAT Galactic Center excess and the 511 keV positron-annihilation signal from the inner Galaxy bare a striking morphological similarity. We propose that both can be explained through a scenario in which millisecond pulsars produce…

High Energy Astrophysical Phenomena · Physics 2018-08-15 Richard Bartels , Francesca Calore , Emma Storm , Christoph Weniger

The cosmic-ray positron flux calculated using the cosmic-ray nuclei interactions in our Galaxy cannot explain observed data above 10 GeV. An excess in the measured positron flux is therefore open to interpretation. Nearby pulsars, located…

High Energy Astrophysical Phenomena · Physics 2017-10-04 Jagdish C. Joshi , Soebur Razzaque

Gamma-ray telescopes are capable of measuring radioactive trace isotopes from cosmic nucleosynthesis events. Such measurements address new isotope production rather directly for a few key isotopes such as 44Ti, 26Al, 60Fe, and 56Ni, as well…

High Energy Astrophysical Phenomena · Physics 2015-05-13 Roland Diehl

Electron-positron annihilation radiation from the Galactic Center region has been detected since the seventies, but its astrophysical origin is still a topic of a scientific debate. We have analyzed data of the gamma-ray imager IBIS/ISGRI…

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