Wuppertal 2015 – scientific programme

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T: Fachverband Teilchenphysik

T 27: Gammaastronomie II

T 27.9: Talk

Monday, March 9, 2015, 18:45–19:00, I.13.71 (HS 28)

Fermi Bubbles and bubble-like emission from the Galactic Plane — Wim de Boer and •Markus Weber — KIT, IEKP, Karlsruhe

The diffuse gamma-ray sky revealed ’Bubbles’ of emission above and below the Galactic Plane symmetric around the centre of the Milky Way with a height of 10 kpc in both directions. From a novel template fit, which allows a simultaneous determination of the signal and foreground in any direction, we find that bubble-like emission is not only found in the halo, but in the Galactic plane as well with a width in latitude coinciding with the molecular clouds. The longitude distribution has a width corresponding to the Galactic bar with an additional contribution from the Scutum-Centaurus arm. The energy spectrum of the Bubbles coincides with the predicted contribution from CRs trapped in sources (SCRs). Also the energetics fits well. Hence, we conclude that the bubble-like emission has a hadronic origin, which arises from SCRs and the Bubbles in the halo arise from hadronic interactions in advected gas. Evidence for advection is provided by the ROSAT X-rays from hot gas in the Bubble region. We find that the morphology of the bubble-like emission in the plane coincides with the morphology of ²⁶Al, which is an outflow from SNRs. This strongly supports the interpretation of the Bubbles and bubble-like emission originating from SCRs.