Fitting the Fermi-LAT GeV excess: On the importance of including the propagation of electrons from dark matter

Lacroix, Thomas; Boehm, Céline; Silk, Joseph

doi:10.1103/physrevd.90.043508

Fitting the Fermi-LAT GeV excess: On the importance of including the propagation of electrons from dark matter

Lacroix, Thomas; Boehm, Céline; Silk, Joseph

Authors

Thomas Lacroix

Céline Boehm

Joseph Silk

Abstract

An excess of gamma rays at GeV energies has been pointed out in the Fermi-LAT data. This signal comes from a narrow region centred around the Galactic center and has been interpreted as possible evidence for light dark matter particles annihilating either into a mixture of leptons-antileptons and bb¯ or into bb¯ only. Focusing on the prompt gamma-ray emission, previous works found that the best fit to the data corresponds to annihilations proceeding predominantly into bb¯. However, here we show that omitting the photon emission originating from primary and secondary electrons produced in dark matter annihilations, and undergoing diffusion through the Galactic magnetic field, can actually lead to the wrong conclusion. Accounting for this emission, we find that not only are annihilations of ∼10 GeV particles into a purely leptonic final state allowed, but the democratic scenario actually provides a better fit to the spectrum of the excess than the pure bb¯ channel. We conclude our work with a discussion on constraints on these leptophilic scenarios based on the AMS data and the morphology of the excess.

Citation

Lacroix, T., Boehm, C., & Silk, J. (2014). Fitting the Fermi-LAT GeV excess: On the importance of including the propagation of electrons from dark matter. Physical Review D, 90(4), Article 043508. https://doi.org/10.1103/physrevd.90.043508

Journal Article Type	Article
Publication Date	Aug 8, 2014
Deposit Date	Feb 3, 2016
Publicly Available Date	Aug 23, 2016
Journal	Physical Review D
Print ISSN	2470-0010
Electronic ISSN	2470-0029
Publisher	American Physical Society
Peer Reviewed	Peer Reviewed
Volume	90
Issue	4
Article Number	043508
DOI	https://doi.org/10.1103/physrevd.90.043508

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