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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
physics and astronomy
The 511 keV emission from positron annihilation in the Galaxy
Reviews of Modern Physics, Volume 83, No. 3, Year 2011
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Description
The first γ-ray line originating from outside the Solar System that was ever detected is the 511 keV emission from positron annihilation in the Galaxy. Despite 30 years of intense theoretical and observational investigation, the main sources of positrons have not been identified up to now. Observations in the 1990s with OSSE/CGRO (Oriented Scintillation Spectrometer Experiment on GRO satellite/Compton Gamma Ray Observatory) showed that the emission is strongly concentrated toward the Galactic bulge. In the 2000s, the spectrometer SPI aboard the European Space Agency's (ESA) International Gamma Ray Astrophysics Laboratory (INTEGRAL) allowed scientists to measure that emission across the entire Galaxy, revealing that the bulge-to-disk luminosity ratio is larger than observed at any other wavelength. This mapping prompted a number of novel explanations, including rather "exotic" ones (e.g., dark matter annihilation). However, conventional astrophysical sources, such as type Ia supernovae, microquasars, or x-ray binaries, are still plausible candidates for a large fraction of the observed total 511 keV emission of the bulge. A closer study of the subject reveals new layers of complexity, since positrons may propagate far away from their production sites, making it difficult to infer the underlying source distribution from the observed map of 511 keV emission. However, in contrast to the rather well-understood propagation of high-energy (>GeV) particles of Galactic cosmic rays, understanding the propagation of low-energy (∼MeV) positrons in the turbulent, magnetized interstellar medium still remains a formidable challenge. The spectral and imaging properties of the observed 511 keV emission are reviewed and candidate positron sources and models of positron propagation in the Galaxy are critically discussed. © 2011 American Physical Society.
Authors & Co-Authors
Prantzos, Nikolas
France, Paris
Institut D’astrophysique de Paris
Boehm, Celine
France, Annecy
Laboratoire D'annecy-le-vieux de Physique Des Particules Lapp
Bykov, Andrei M.
Russian Federation, Saint Petersburg
Ioffe Institute
Diehl, Roland D.
Germany, Garching Bei Munchen
Max Planck Institute for Extraterrestrial Physics
Ferrière, Katia M.
France, Toulouse
Université Fédérale Toulouse Midi-pyrénées
Guessoum, Nidhal
United Arab Emirates, Sharjah
American University of Sharjah
Jean, Pierre
France, Toulouse
Université Fédérale Toulouse Midi-pyrénées
Knoedlseder, J.
France, Toulouse
Université Fédérale Toulouse Midi-pyrénées
Marcowith, Alexandre
France, Montpellier
Laboratoire Univers et Particules de Montpellier
Moskalenko, Igor V.
United States, Stanford
Kavli Institute for Particle Astrophysics and Cosmology
Strong, Andrew W.
Germany, Garching Bei Munchen
Max Planck Institute for Extraterrestrial Physics
Weidenspointner, Georg
Germany, Garching Bei Munchen
Max Planck Institute for Extraterrestrial Physics
Germany, Munich
Halbleiterlabor Der Max-planck-gesellschaft
Statistics
Citations: 12
Authors: 12
Affiliations: 9
Identifiers
Doi:
10.1103/RevModPhys.83.1001
ISSN:
00346861
e-ISSN:
15390756
Research Areas
Environmental
Study Approach
Quantitative