Connecting the new H.E.S.S. diffuse emission at the Galactic Center with the Fermi GeV excess: A combination of millisecond pulsars and heavy dark matter?

Lacroix, Thomas; Silk, Joseph; Moulin, Emmanuel; Boehm, Celine

Abstract

The H.E.S.S. Collaboration has reported a high-energy spherically symmetric diffuse γ-ray emission in the inner 50 pc of the Milky Way, up to ∼50 TeV. Here, we propose a leptonic model which provides an alternative to the hadronic scenario presented by the H.E.S.S. Collaboration, and connects the newly reported TeV emission to the Fermi-LAT Galactic Center GeV excess. Our model relies on a combination of inverse Compton emission from a population of millisecond pulsars—which can account for the GeV excess—and a supermassive black hole-induced spike of heavy (∼60 TeV) dark matter particles annihilating into electrons with a subthermal cross section. With an up-to-date interstellar radiation field, as well as a standard magnetic field and diffusion setup, our model accounts for the spectral morphology of the detected emission. Moreover, we show that the dark matter-induced emission reproduces the spatial morphology of the H.E.S.S. signal above ∼10 TeV, while we obtain a slightly more extended component from pulsars at lower energies, which could be used as a prediction for future H.E.S.S. observations.

Citation

Lacroix, T., Silk, J., Moulin, E., & Boehm, C. (2016). Connecting the new H.E.S.S. diffuse emission at the Galactic Center with the Fermi GeV excess: A combination of millisecond pulsars and heavy dark matter?. Physical Review D, 94(12), Article 123008. https://doi.org/10.1103/physrevd.94.123008

• Journal Article Type: Article
• Acceptance Date: Mar 20, 2016
• Online Publication Date: Dec 12, 2016
• Publication Date: Dec 12, 2016
• Deposit Date: Jun 19, 2016
• Publicly Available Date: Aug 21, 2018
• Journal: Physical Review D
• Print ISSN: 2470-0010
• Electronic ISSN: 2470-0010
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 94
• Issue: 12
• Article Number: 123008
• DOI: https://doi.org/10.1103/physrevd.94.123008