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Multi-Component Dark Matter as a Solution to the Galactic Center GeV Excess

Farinaldo S. Queiroz, Clarissa Siqueira, Carlos E. Yaguna

Abstract

The Galactic Center Excess (GCE) is a compelling signature of dark matter annihilation, but its spectral morphology is difficult to reconcile with the traditional paradigm of a single particle species. In this work, we perform a systematic investigation of multi-component dark matter sectors, exploring scenarios with two ($N=2$) and three ($N=3$) distinct particle species while considering both exclusive and mixed annihilation channels. Using the Akaike Information Criterion (AIC) to rigorously penalize model complexity, we find that the GCE data statistically favors an $N=2$ scenario where each dark matter component annihilates exclusively into a single final state. Our results reveal that the preferred solutions naturally follow a light-plus-heavy mass hierarchy, and that specific final states such as $t\bar{t}$, $ZZ$, and $hh$, which are individually unable to explain the excess are effectively ``resurrected'' by the improved morphological fit provided by the multi-component framework. Furthermore, we show that these scenarios may mitigate the tension with current constraints, reaching compatibility within existing uncertainties. Our results suggest that the GCE may be the first evidence of a diverse dark sector, favoring a multi-scale solution over the minimal WIMP paradigm.

Multi-Component Dark Matter as a Solution to the Galactic Center GeV Excess

Abstract

The Galactic Center Excess (GCE) is a compelling signature of dark matter annihilation, but its spectral morphology is difficult to reconcile with the traditional paradigm of a single particle species. In this work, we perform a systematic investigation of multi-component dark matter sectors, exploring scenarios with two () and three () distinct particle species while considering both exclusive and mixed annihilation channels. Using the Akaike Information Criterion (AIC) to rigorously penalize model complexity, we find that the GCE data statistically favors an scenario where each dark matter component annihilates exclusively into a single final state. Our results reveal that the preferred solutions naturally follow a light-plus-heavy mass hierarchy, and that specific final states such as , , and , which are individually unable to explain the excess are effectively ``resurrected'' by the improved morphological fit provided by the multi-component framework. Furthermore, we show that these scenarios may mitigate the tension with current constraints, reaching compatibility within existing uncertainties. Our results suggest that the GCE may be the first evidence of a diverse dark sector, favoring a multi-scale solution over the minimal WIMP paradigm.
Paper Structure (16 sections, 9 equations, 3 figures, 6 tables)

This paper contains 16 sections, 9 equations, 3 figures, 6 tables.

Table of Contents

  1. Introduction
  2. Theoretical framework
  3. Gamma-Ray Flux and Effective Cross-Section
  4. Model Parameters and Degrees of Freedom
  5. Methodology
  6. Results
  7. Baseline: Single-Component Dark Matter ($N=1$)
  8. Two-Component Dark Matter ($N=2$)
  9. Mixed Annihilation Channels
  10. Three-Component Dark Matter ($N=3$)
  11. Exclusive Annihilation Channels
  12. Single-Mixed Scenario
  13. Discussion
  14. Degeneracy and the Window of Viability
  15. Constraints from Independent Searches
  16. ...and 1 more sections

Figures (3)

  • Figure 1: Predicted flux for one DM component annihilating into $\bar{b}b$ compared with the Fermi-LAT data, including statistical and systematic uncertainties (left panel) and the benchmark point including $1\sigma$ and $2\sigma$ contours compared to the dSphs limits.
  • Figure 2: Fluxes generated by two dark matter components combined, given the best fit to the Fermi-LAT data for several possible channels, $\bar{b}b$ and $WW$, $\bar{q}q$ and $WW$, $\tau^+\tau^-$ and $ZZ$, and $\tau^+\tau^-$ and $WW$, with the first contribution given in blue, the second one in green and the combined flux in black. The gray dots are the Fermi-LAT data, including statistical and systematic errors.
  • Figure 3: The best-fit $1\sigma$ and $2\sigma$ regions for four representative scenarios in our exclusive two-component fit ($N=2$), compared with exclusion limits from Fermi-LAT dSphs and AMS-02 antiprotons. Systematic uncertainties in the $J$-factors and propagation models may shift these exclusion boundaries, potentially resolving regions of apparent tension.