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

Journal Article · 12 July 2023 · Monthly Notices of the Royal Astronomical Society

DOI: https://doi.org/10.1093/mnras/stad2074 · OSTI ID:1992933

Evans, Addy J. ; Strigari, Louis E. ; Svenborn, Oskar; Albert, Andrea; Harding, J. Patrick; Hooper, Dan; Linden, Tim; Pace, Andrew B.

ABSTRACT We use Fermi-LAT data to analyse the faint gamma-ray source located at the centre of the Sagittarius (Sgr) dwarf spheroidal galaxy. In the 4FGL-DR3 catalogue, 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 favours a dark matter mass of mχ = 29.6 ± 5.8 GeV and an annihilation cross section of $$\sigma v = (2.1 \pm 0.59) \times 10^{-26} \, \text{cm}^3$$ s−1 for the $$b \bar{b}$$ channel (or mχ = 8.3 ± 3.8 GeV and $$\sigma v = (0.90 \pm 0.25) \times 10^{-26} \, \text{cm}^3$$ s−1 for the τ+τ− channel), when adopting a J-factor of $$J=10^{19.6} \, \text{GeV}^2 \, \text{cm}^{-5}$$. This parameter space is consistent with gamma-ray constraints from other dwarf galaxies and with dark matter interpretations of the Galactic Centre Gamma-Ray Excess.

• Research Organization: Carnegie Mellon U.; Chicago U., Astron. Astrophys. Ctr.; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Stockholm U.; Stockholm U., OKC; Texas A-M
• Sponsoring Organization: US Department of Energy; USDOE
• Grant/Contract Number: 89243024CSC000002; AC02-07CH11359; SC0010813
• OSTI ID: 1992933
• Report Number(s): FERMILAB-PUB-22-890-T
• Journal Information: Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 3 Vol. 524; ISSN 0035-8711
• Publisher: Oxford University PressCopyright Statement
• Country of Publication: United Kingdom
• Language: English