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

Abstract

We use data from the Large Area Telescope onboard the Fermi gamma-ray space telescope (Fermi-LAT) 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, which is coincident with the dynamical center of this dwarf galaxy. 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 that this signal favors a dark matter mass of $m_{\chi }=29.6\pm 5.8$ GeV and an annihilation cross section of $\sigma v=(2.1\pm 0.59)\times 10^{-26}{\text{cm}}^3/$s for the $b\bar{b}$ channel (or $m_{\chi }=8.3\pm 3.8$ GeV and $\sigma v=(0.90\pm 0.25)\times 10^{-26}{\text{cm}}^3/$s for the ${\tau }^{+}{\tau }^{-}$ 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 Center Gamma-Ray Excess.

12 pages, 9 figures. To be submitted to MNRAS -- comments welcome

References in corpus (20)

• Array Programming with NumPy
• Precise Relic WIMP Abundance and its Impact on Searches for Dark Matter Annihilation
• Searching for Dark Matter Annihilation in Recently Discovered Milky Way Satellites with Fermi-LAT
• Background model systematics for the Fermi GeV excess
• Accurate distances to Galactic globular clusters through a combination of Gaia EDR3, HST and literature data
• Kraken reveals itself -- the merger history of the Milky Way reconstructed with the E-MOSAICS simulations
• Search for dark matter annihilation signatures in H.E.S.S. observations of Dwarf Spheroidal Galaxies
• The last breath of the Sagittarius dSph
• Density and kinematic cusps in M54 at the heart of the Sagittarius dwarf galaxy: evidence for a 10^4 M_sun Black Hole?
• The Return of the Templates: Revisiting the Galactic Center Excess with Multi-Messenger Observations
• Can Astrophysical Gamma Ray Sources Mimic Dark Matter Annihilation in Galactic Satellites?
• Distance to the Sagittarius Dwarf Galaxy using MACHO Project RR Lyrae stars
• Evidence that Ultra-High-Energy Gamma Rays are a Universal Feature Near Powerful Pulsars
• Evidence of TeV Halos Around Millisecond Pulsars
• Estimating the GeV Emission of Millisecond Pulsars in Dwarf Spheroidal Galaxies
• Evidence for a high-energy tail in the gamma-ray spectra of globular clusters
• Discovery of new globular clusters in the Sagittarius dwarf galaxy
• Eight more low luminosity globular clusters in the Sagittarius dwarf galaxy
• The Dark Matter Halo of M54
• A search for stellar X-ray sourcesin the Sagittarius and Carina dwarf galaxies - I: X-ray observations

Cited by in corpus (3)

• Dark Matter Candidates and Searches
• Kinematics of the Sagittarius Dwarf Spheroidal core: A 5D Analysis for a 6D Methodology with Gaia DR3
• Millisecond Pulsars in Globular Clusters and Implications for the Galactic Center Gamma-Ray Excess