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Volume 285 - 11th INTEGRAL Conference Gamma-Ray Astrophysics in Multi-Wavelength Perspective (INTEGRAL2016) - Nucleosynthesis and gamma-ray lines
Positron annihilation in the Milky Way and beyond
T. Siegert
Full text: pdf
Pre-published on: 2017 July 18
Published on: 2017 August 23
The electron-positron annihilation gamma-ray signal at 511 keV in the Milky Way is investigated towards a possible dark matter interpretation. If all bulge positrons were created by dark matter particle annihilation, the satellite galaxies of the Milky Way, apparently being dominated by dark matter, should also show measurable 511 keV signals. Using INTEGRAL/SPI, we test for emission in 39 neighbouring dwarf satellite galaxies, and found a consistent trend against a dark matter scenario. One galaxy, Reticulum II, shows up as a strong source of annihilation emission, which we interpret as the presence of a microquasar, ejecting pair-plasma into the galaxy's interstellar medium.
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