GeV excess in the Milky Way: The role of diffuse galactic gamma-ray emission templates

By Bei Zhou, Yun-Feng Liang, Xiaoyuan Huang, Xiang Li, Yizhong Fan, Lei Feng, Jin Chang. 2014

139 citations recorded by the source corpus.

Several groups have analyzed the publicly available Fermi-LAT data and have reported a spatially extended. ray excess of around 1-3 GeV from the region surrounding the Galactic center that might originate from annihilation of dark-matter particles with a rest mass m(chi) similar to 30-40 GeV. In this work we examine the role of the diffuse galactic gamma-ray emission templates played in suppressing the GeV excess. For such a purpose, we adopt in total 128 background templates that were generated by Ackermann et al. [Astrophys. J. 750, 3 (2012)] in the study of the Fermi-LAT observations of the diffuse gamma-ray emission considering the effects of cosmic rays and the interstellar medium. The possible GeV excess, assumed to follow the spatial distribution of the prompt gamma rays produced in the annihilation of dark-matter particles taking a generalized Navarro-Frenk-White profile with an inner slope alpha=1.2, has been analyzed in some regions of interest. The introduction of such an additional component centered at the Galactic center is found to have improved the goodness of fit to the data significantly in all background template models regardless of whether the excess spectrum is fixed or not. Our results thus suggest that the presence of a statistically significant GeV excess in the inner Galaxy is robust, though its spectrum depends on the diffuse galactic gamma-ray emission model adopted in the analysis. The possible physical origin of the GeV excess component is discussed and, in the dark-matter model, the annihilation cross section of such particles is evaluated.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/db88e088a2ddc685a3be62412610a0c0c9a70fe5

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Citations in the corpus

Sensitivity projections for dark matter searches with the Fermi large area telescope (2016, background): “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].”
Gravitational probes of dark matter physics (2017, background): “Indirect detection searches for dark matter annihilation or decay in the Universe today can improve signal over background by targeting high-density regions — be it the Galactic Center [441, 442, 443, 444, 445, 446, 447, 448, 449, 450, 451, 452, 453, 454, 455, 456], satellite galaxies [457, 458, 459”
The Fermi Galactic Center GeV Excess and Implications for Dark Matter (2017, background): “…2009; Vitale et al. 2009; Hooper & Goodenough 2011; Abazajian & Kaplinghat 2012; Gordon & Macías 2013; Hooper & Slatyer 2013; Calore et al. 2015; Zhou et al. 2015; Ajello et al. 2016; Daylan et al. 2016), while other groups refuted the existence of an excess after considering the uncertainties…”
WIMP dark matter candidates and searches—current status and future prospects (2017, methodology): “The Fermi-LAT Collaboration released their own analysis [288] in which GCE is studied employing multiple specialized interstellar emission models (IEMs) that enabled to separate the signal coming from the region surrounding the GC (within ∼1 kpc) from the rest of the Galaxy (see also [289, 290] for ”