  Excess microwave emission observed in the inner Galaxy (inner ~1 kpc) is
consistent with synchrotron emission from highly relativistic electron-positron
pairs produced by dark matter particle annihilation. More conventional sources
for this emission, such as free-free (thermal bremsstrahlung), thermal dust,
spinning dust, and the softer Galactic synchrotron traced by low-frequency
surveys, have been ruled out. The total power observed in the range 23 < nu <
61 GHz is between 10^{36} and 5x10^{36} erg/s, depending on the method of
extrapolation to the Galactic center, where bright foreground emission obscures
the signal. The inferred electron energy distribution is diffusion hardened,
and is in qualitative agreement with the energy distribution required to
explain the gamma ray excess in the inner Galaxy at 1-30 GeV as inverse-Compton
scattered starlight. We investigate the possibility that this population of
electrons is produced by dark matter annihilation of 100 GeV particles, with
cross section <sigma v>=2x10^{-26} cm^3/s, and an 1/r dark matter mass profile
truncated in the inner Galaxy, and find this scenario to be consistent with
current data.
