Bremsstrahlung gamma rays from light dark matter
- Institut de Physique Théorique, CNRS, URA 2306 and CEA/Saclay, Gif-sur-Yvette, F-91191 (France)
- Laboratoire de Physique Théorique d'Annecy-le-Vieux (LAPTh), Université de Savoie, CNRS, B.P.110, Annecy-le-Vieux, F-74941 (France)
- Abdus Salam International Centre for Theoretical Physics (ICTP) Strada Costiera 11, Trieste, 34151 (Italy)
We discuss the often-neglected role of bremsstrahlung processes on the interstellar gas in computing indirect signatures of Dark Matter (DM) annihilation in the Galaxy, particularly for light DM candidates in the phenomenologically interesting O(10) GeV mass range. Especially from directions close to the Galactic Plane, the γ-ray spectrum is altered via two effects: directly, by the photons emitted in the bremsstrahlung process by energetic electrons which are among the DM annihilation byproducts; indirectly, by the modification of the same electron spectrum, due to the additional energy loss process in the diffusion-loss equation (e.g. the resulting inverse Compton emission is altered). We quantify the importance of the bremsstrahlung emission in the GeV energy range, showing that it is sometimes the dominant component of the γ-ray spectrum. We also find that, in regions in which bremsstrahlung dominates energy losses, the related γ-ray emission is only moderately sensitive to possible large variations in the gas density. Still, we stress that, for computing precise spectra in the (sub-)GeV range, it is important to obtain a reliable description of the Galaxy gas distribution as well as to compute self-consistently the γ-ray emission and the solution to the diffusion-loss equation. For example, these are crucial issues to quantify and interpret meaningfully γ-ray map 'residuals' in the inner Galaxy.
- OSTI ID:
- 22369924
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2013, Issue 11; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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