A tale of tails: Dark matter interpretations of the Fermi GeV excess in light of background model systematics

By F. Calore, I. Cholis, C. McCabe, Christoph Weniger. 2014

255 citations recorded by the source corpus.

Several groups have identified an extended excess of gamma rays over the modeled foreground and background emissions towards the Galactic center (GC) based on observations with the Fermi Large Area Telescope. This excess emission is compatible in morphology and spectrum with a telltale sign from dark matter (DM) annihilation. Here, we present a critical reassessment of DM interpretations of the GC signal in light of the foreground and background uncertainties that some of us recently outlaid in Calore et al. (2014). We find that a much larger number of DM models fits the gamma-ray data than previously noted. In particular: (1) In the case of DM annihilation into (b) over barb, we find that even large DM masses up to m(chi) similar or equal to 74 GeV are allowed at p-value > 0.05. (2) Surprisingly, annihilation into nonrelativistic hh gives a good fit to the data. (3) The inverse Compton emission from mu(+)mu(-) with m(chi) similar to 60-70 GeV can also account for the excess at higher latitudes, vertical bar b vertical bar > 2 degrees, both in its spectrum and morphology. We also present novel constraints on a large number of mixed annihilation channels, including cascade annihilation involving hidden sector mediators. Finally, we show that the current limits from dwarf spheroidal observations are not in tension with a DM interpretation when uncertainties on the DM halo profile are accounted for.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/87f95ceea8f22c08cd9e61100f6347e3faa9c0d5

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Citations in the corpus

The effects of QCD equation of state on the relic density of WIMP dark matter (2015, background): “It has been claimed that there is evidence for an additional component in the GeV γ flux from near the galactic center which can be explained through WIMP annihilation [54–57], but other interpretations of this additional component exist [58–60].”
Sensitivity projections for dark matter searches with the Fermi large area telescope (2016, methodology): “Although the existence and spatial extension of the excess have been found to be robust against uncertainties of modeling the Galactic diffuse γ-ray emission, the measured spectrum of the excess has been shown to depend strongly on the Galactic diffuse emission model [67, 67, 81, 84, 85].”
A taste of dark matter: flavour constraints on pseudoscalar mediators (2014, unknown): “Uncertainties in the DM halo parameters translate to about a factor five uncertainty in the annihilation cross section [24], so we do not quote a more precise value.”
FERMI-LAT OBSERVATIONS OF HIGH-ENERGY γ-RAY EMISSION TOWARD THE GALACTIC CENTER (2015, methodology): “…the same Galactocentric radial boundaries as the π0-decay templates, and allowing for spectral variations in the π0-decay templates from those predicted interior to the solar circle – that go beyond the modelling of the interstellar emission employed by other analyses (e.g., Calore et al. 2015b).”