No abstract

We use Fermi-LAT data to analyze the faint gamma-ray source located at the center of the Sagittarius (Sgr) dwarf spheroidal galaxy. In the 4FGL-DR3 catalog, this source is associated with the globular cluster, M54. We investigate the spectral energy distribution and spatial extension of this source, with the goal of testing two hypotheses: (1) the emission is due to millisecond pulsars within M54, or (2) the emission is due to annihilating dark matter from the Sgr halo. For the pulsar interpretation, we consider a two-component model which describes both the lower-energy magnetospheric emission and possible high-energy emission arising from inverse Compton scattering. We find that this source has a point-like morphology at low energies, consistent with magnetospheric emission, and find no evidence for a higher-energy component. For the dark matter interpretation, we find the signal favors a dark matter mass of mχ = 29.6 ± 5.8 GeV and an annihilation cross section of σv = (2.1 ± 0.59) × 10−26 cm3 s−1 for the $b \bar{b}$ channel (or mχ = 8.3 ± 3.8 GeV and σv = (0.90 ± 0.25) × 10−26 cm3 s−1 for the τ+τ− channel), when adopting a J-factor of J = 1019.6 GeV2 cm−5. This parameter space is consistent with gamma-ray constraints from other dwarf galaxies and with dark matter interpretations of the Galactic Center Gamma-Ray Excess.