The ATLAS 9.0 GHz Survey of the Extended Chandra Deep Field South: The
  Faint 9.0 GHz Radio Population
  We present a new image of the 9.0 GHz radio emission from the extended
Chandra Deep Field South. A total of 181 hours of integration with the
Australia Telescope Compact Array has resulted in a 0.276 square degree image
with a median sensitivity of $\sim$20 $\mu$Jy/beam rms, for a synthesised beam
of 4.0 $\times$ 1.3 arcsec. We present a catalogue of the 9.0 GHz radio
sources, identifying 70 source components and 55 individual radio galaxies.
Source counts derived from this sample are consistent with those reported in
the literature. The observed source counts are also generally consistent with
the source counts from simulations of the faint radio population. Using the
wealth of multiwavelength data available for this region, we classify the faint
9 GHz population and find that 91% are radio loud AGN, 7% are radio quiet AGN
and 2% are star forming galaxies. The 9.0 GHz radio sources were matched to 5.5
and 1.4 GHz sources in the literature and we find a significant fraction of
flat or inverted spectrum sources, with 36% of the 9 GHz sources having
$\alpha_{5.5GHz}^{9.0GHz}$ $>$ -0.3 (for $S \propto \nu^\alpha$). This flat or
inverted population is not well reproduced by current simulations of radio
source populations.
