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We use data from the Large Area Telescope onboard the Fermi gamma-ray spacetelescope (Fermi-LAT) to analyze the faint gamma-ray source located at thecenter of the Sagittarius (Sgr) dwarf spheroidal galaxy. In the 4FGL-DR3catalog, this source is associated with the globular cluster, M54, which iscoincident with the dynamical center of this dwarf galaxy. We investigate thespectral energy distribution and spatial extension of this source, with thegoal of testing two hypotheses: (1) the emission is due to millisecond pulsarswithin M54, or (2) the emission is due to annihilating dark matter from the Sgrhalo. For the pulsar interpretation, we consider a two-component model whichdescribes both the lower-energy magnetospheric emission and possiblehigh-energy emission arising from inverse Compton scattering. We find that thissource has a point-like morphology at low energies, consistent withmagnetospheric emission, and find no evidence for a higher-energy component.For the dark matter interpretation, we find that this signal favors a darkmatter mass of $m_{\chi} = 29.6 \pm 5.8$ GeV and an annihilation cross sectionof $\sigma v = (2.1 \pm 0.59) \times 10^{-26} \,\text{cm}^3/$s for the $b\bar{b}$ channel (or $m_{\chi} = 8.3 \pm 3.8$ GeV and $\sigma v = (0.90 \pm0.25) \times 10^{-26} \, \text{cm}^3/$s for the $\tau^+ \tau^-$ channel), whenadopting a J-factor of $J=10^{19.6} \, \text{GeV}^2 \, \text{cm}^{-5}$. Thisparameter space is consistent with gamma-ray constraints from other dwarfgalaxies and with dark matter interpretations of the Galactic Center Gamma-RayExcess.

On the gamma-ray emission from the core of the Sagittarius dwarf galaxy