Abstract
Abstract
Well-motivated models of dark matter often result in a population of electrons and positrons within galaxies produced through dark matter annihilation — usually in association with gamma rays. As they diffuse through galactic magnetic fields, these e± produce synchrotron radio emission. The intensity and morphology of this signal depends on the properties of the interstellar medium through which the e± propagate. Using observations of the Andromeda Galaxy (M31) to construct a model of the gas, magnetic fields, and starlight, we set constraints on dark matter annihilation to $$ b\overline{b} $$
b
b
¯
using the morphology of 3.6 cm radio emission. As the emission signal at the center of M31 is very sensitive to the diffusion coefficient and dark matter profile, we base our limits on the differential flux in the region between 0.9 – 6.9 kpc from the center. We exclude annihilation cross sections ≳ 3 × 10−25 cm3/s in the mass range 10 – 500 GeV, with a maximum sensitivity of 7 × 10−26 cm3/s at 20 – 40 GeV. Though these limits are weaker than those found in previous studies of M31, they are robust to variations of the diffusion coefficient.
Publisher
Springer Science and Business Media LLC
Subject
Nuclear and High Energy Physics
Reference91 articles.
1. D.J. Bartlett et al., Constraints on dark matter annihilation and decay from the large-scale structure of the nearby Universe, Phys. Rev. D 106 (2022) 103526 [arXiv:2205.12916] [INSPIRE].
2. Fermi-LAT collaboration, Observations of M31 and M33 with the Fermi Large Area Telescope: A Galactic Center Excess in Andromeda?, Astrophys. J. 836 (2017) 208 [arXiv:1702.08602] [INSPIRE].
3. C.M. Karwin et al., Dark matter interpretation of the Fermi-LAT observations toward the outer halo of M31, Phys. Rev. D 103 (2021) 023027 [arXiv:2010.08563] [INSPIRE].
4. M.R. Buckley et al., Search for Gamma-ray Emission from Dark Matter Annihilation in the Large Magellanic Cloud with the Fermi Large Area Telescope, Phys. Rev. D 91 (2015) 102001 [arXiv:1502.01020] [INSPIRE].
5. R. Caputo et al., Search for Gamma-ray Emission from Dark Matter Annihilation in the Small Magellanic Cloud with the Fermi Large Area Telescope, Phys. Rev. D 93 (2016) 062004 [arXiv:1603.00965] [INSPIRE].