Foreground Predictions for the Cosmic Microwave Background Power
  Spectrum from Measurements of Faint Inverted Radio Sources at 5 GHz
  We present measurements of a population of matched radio sources at 1.4 and 5
GHz down to a flux limit of 1.5 mJy in 7 sq. degs. of the NOAO Deep Field
South. We find a significant fraction of sources with inverted spectral indices
that all have 1.4 GHz fluxes less than 10 mJy, and are therefore too faint to
have been detected and included in previous radio source count models that are
matched at multiple frequencies. Combined with the matched source population at
1.4 and 5 GHz in 1 sq. deg. in the ATESP survey, we update models for the 5 GHz
differential number counts and distributions of spectral indices in 5 GHz flux
bins that can be used to estimate the unresolved point source contribution to
the cosmic microwave background temperature anisotropies. We find a shallower
logarithmic slope in the 5 GHz differential counts than in previously published
models for fluxes < 100 mJy as well as larger fractions of inverted spectral
indices at these fluxes. Because the Planck flux limit for resolved sources is
larger than 100 mJy in all channels, our modified number counts yield at most a
10% change in the predicted Poisson contribution to the Planck temperature
power spectrum. For a flux cut of 5 mJy with the South Pole Telescope and a
flux cut of 20 mJy with the Atacama Cosmology Telescope we predict a ~30% and
~10% increase, respectively, in the radio source Poisson power in the lowest
frequency channels of each experiment relative to that predicted by previous
models.
