• Accepted Paper

Wino and real minimal dark matter disfavored by Fermi gamma-ray observations

Benjamin R. Safdi and Weishuang Linda Xu

Phys. Rev. D - Accepted 4 August, 2026

DOI: https://doi.org/10.1103/pc9s-b56k

Abstract

We show that minimal, fermionic dark matter (DM) models in the n-dimensional representation of the weak force with zero hypercharge that make up 100% of the DM under the standard cosmological history are strongly disfavored for n<9. This includes the thermal wino, which we show is ruled out even allowing for DM core sizes up to $$6.7 kpc with the preferred local DM density or $$3.7 kpc in addition to the local DM density being half the preferred value, at less than 0.2 GeV/cm3. We reach these conclusions through dedicated searches with 14 years of Fermi gamma-ray data in the inner Galaxy between 30 GeV and 2 TeV for the continuum gamma-rays produced in the decays of unstable particles produced in DM annihilation and bound-state formation processes. We consider a variety of Milky Way DM profiles in our analyses, including those motivated by modern hydrodynamic cosmological simulations, and show that all the n<9 minimal DM models are disfavored even under the most conservative assumptions for these density profiles. While wino, quintuplet (n=5), and n=7 DM models are strongly disfavored by our analyses under the standard cosmology, we discuss how non-standard cosmological histories or DM sub-fractions could still allow for these particles to be realized in nature, with discovery opportunities at next-generation particle colliders and gamma-ray telescopes.

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