High Frequency GPS sources in the AT20G Survey
  The Australia Telescope 20GHz (AT20G) survey was used to select a complete
sample of 656 Gigahertz Peaked Spectrum (GPS) sources with spectral turnovers
above 5GHz. The AT20G has near simultaneous observations at 4.8, 8.6 and 20GHz,
which makes it possible to exclude flat spectrum variability as a cause of a
source's peaked spectrum. Optical identification of the sample results in 361
QSOs and 104 galaxies and 191 blank fields. Redshifts are known for 104 of the
GPS sources. The GPS sources from the AT20G are discussed and compared to
previously known samples. The new sample of high frequency peaking GPS sources
is found at a lower redshift than previous samples and to also have a lower
5GHz radio power. Evidence is found to support the idea that the origin of the
GPS spectral shape are intrinsically different for galaxies and QSOs. This
paper is an elaboration and extension of the talk given at the $4^{th}$ CSS/GPS
conference in Riccione in May 2008.
