Observations by ARCADE-2 and other telescopes sensitive to low frequency radiation have revealed the presence of an isotropic radio background with a hard spectral index .
The intensity of this observed background is found to exceed the flux predicted from astrophysical sources by a factor of approximately 5-6 .
In this article , we consider the possibility that annihilating dark matter particles provide the primary contribution to the observed isotropic radio background through the emission of synchrotron radiation from electron and positron annihilation products .
For reasonable estimates of the magnetic fields present in clusters and galaxies , we find that dark matter could potentially account for the observed radio excess , but only if it annihilates mostly to electrons and/or muons , and only if it possesses a mass in the range of approximately 5-50 GeV .
For such models , the annihilation cross section required to normalize the synchrotron signal to the observed excess is \sigma v \approx ( 0.4 - 30 ) \times 10 ^ { -26 } cm ^ { 3 } /s , similar to the value predicted for a simple thermal relic ( \sigma v \approx 3 \times 10 ^ { -26 } cm ^ { 3 } /s ) .
We find that in any scenario in which dark matter annihilations are responsible for the observed excess radio emission , a significant fraction of the isotropic gamma ray background observed by Fermi must result from dark matter as well .