Erlangen 2026 – wissenschaftliches Programm

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EP: Fachverband Extraterrestrische Physik

EP 2: Astrophysics II

EP 2.7: Vortrag

Montag, 16. März 2026, 17:45–18:00, KH 01.019

Observations of the dark matter halo of the Andromeda Galaxy with INTEGRAL/SPI — •Laura Eisenberger, Thomas Siegert, Saurabh Mittal, Rudi Reinhardt, Dimitris Tsatsis, Niklas C. Bauer, Patrik Ehrmann, and Manja Zimmerer — Julius-Maximilians-Universität Würzburg, Fakultät für Physik und Astronomie, Institut für Theoretische Physik und Astrophysik, Lehrstuhl für Astronomie, Emil-Fischer-Str. 31, 97074 Würzburg

The Andromeda galaxy (M31) is a promising target for the indirect search of dark matter (DM) due to its proximity and expected massive DM halo. It functions as test case for a Milky Way (MW) like galaxy as the isotropic emission from the MW halo itself cannot be measured without large efforts with coded mask telescopes. Since weakly interacting massive particles also produce a significant flux of secondary MeV photons from inverse Compton scattering and positron annihilation, γ-ray observations in the MeV range are a powerful probe of DM with a wide mass range from MeV up to TeV.

We use the spectrum obtained from SPI observations of the M31 region including M33 in order to constrain different DM models. We model the halos of M31 and M33 as extended emission and take the uncertainty of the DM distribution into account by considering different density profiles and substructure boosting. From the 511 keV line from positron annihilation, we estimate the pair production rate in M31 to put a lower mass limit on thermal DM. With forthcoming missions like COSI-SMEX, a coherent multi-galaxy analysis promises to significantly improve upon existing DM constraints.

Keywords: dark matter; galaxies: halos; galaxies: individual (M31); gamma rays: observations