Galaxy clusters in high definition: A dark matter search

Recent radio-frequency probes, with the ATCA and ASKAP telescopes, have proven themselves to be at the forefront of placing indirect limits on the properties of dark matter. The latter being able to substantially exceed the constraining power of Fermi-LAT data. However, these observations were based only on dwarf galaxies, where magnetic field uncertainties are large. Here we reexamine the case for galaxy clusters, often ignored due to substantial diffuse radio backgrounds, by considering the extrapolation of known cluster surface brightness profiles down to scales observable with MeerKAT. Despite large baryonic backgrounds, we find that clusters can be competitive with dwarf galaxies. Extrapolated Coma data being able to rule out weakly interacting massive particles of mass < 700 GeV annihilating via b-quarks. This is while having lesser uncertainties surrounding the magnetic field and diffusive environment. Such compelling results are possible due to a clash between the inner shape of the dark matter halo and the flat inner profile of radio halos which is most pronounced for Navarro-Frenk-White-like Einasto profiles, the presence of which having some supporting evidence in the literature.

Automated summary

Recent radio-frequency probes using the ATCA and ASKAP telescopes have made significant progress in indirectly constraining the properties of dark matter, surpassing the constraining power of Fermi-LAT data. This study reexamines the potential of galaxy clusters, which are often overlooked due to radio backgrounds, by extrapolating known cluster surface brightness profiles observable with MeerKAT. Despite baryonic backgrounds, clusters can compete with dwarf galaxies, with extrapolated Coma data ruling out weakly interacting massive particles of mass < 700 GeV annihilating via b-quarks. This is due to the clash between the inner shape of the dark matter halo and the flat inner profile of radio halos, with supporting evidence in the literature for Navarro-Frenk-White-like Einasto profiles.