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Dark matter annihilation and the Galactic Centre Excess

Grand, RJJ and White, SDM (2022) Dark matter annihilation and the Galactic Centre Excess. Monthly Notices of the Royal Astronomical Society: Letters, 511 (1). L55-L59. ISSN 1745-3925

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We compare the surface brightness profile and morphology of the Galactic Centre Excess (GCE) identified in wide-angle γ-ray maps from the Fermi-Large Area Telescope (LAT) to dark matter annihilation predictions derived from high-resolution Λ cold dark matter magnetohydrodynamic simulations of galaxy formation. These simulations produce isolated, disc-dominated galaxies with structure, stellar populations, gas content, and stellar and halo masses comparable to those of the Milky Way. For a specific choice of annihilation cross-section, they agree well with the Fermi-LAT data over the full observed angular range, 1°-15°, whereas their dark-matter-only counterparts, lacking any compression of the inner halo by the gravitational effects of the baryons, fail to predict emission as centrally concentrated as observed. These results provide additional support to the hypothesis that the GCE is produced by annihilating dark matter. If, however, it is produced by a different mechanism, they imply a strong upper limit on annihilation rates, which can be translated into upper limits on the expected γ-ray flux not only from the inner Galaxy, but also from any substructure, with or without stars, in the Galactic halo.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2022 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: 0201 Astronomical and Space Sciences
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press (OUP)
SWORD Depositor: A Symplectic
Date Deposited: 20 Apr 2023 11:16
Last Modified: 20 Apr 2023 11:16
DOI or ID number: 10.1093/mnrasl/slac011
URI: https://researchonline.ljmu.ac.uk/id/eprint/19281
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