Thomas Siegert
Published 2017-07-21Version 1
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.
Comments: 9 pages, 3 figures, accepted contribution to the 11th INTEGRAL Conference, "Gamma-Ray Astrophysics in Multi-Wavelength Perspective", 10-14 October 2016, Amsterdam, The Netherlands
Hard spectrum of cosmic rays in the Disks of Milky Way and Large Magellanic Cloud
Turbulent mixing of r-process elements in the Milky Way
Evidence for Gamma-ray Jets in the Milky Way
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