1. High-Frequency GPS sources from the AT20G survey Paul Hancock - University of Sydney Australia Ron Ekers (ATNF, PI), Sarah Burke(Swinburne), Mark Calabretta (ATNF), Gianfranco De Zotti (Padua), Paul Hancock (U Sydney), Carole Jackson (ATNF), Michael Kesteven (ATNF), Marcella Massardi (SISSA/ATNF), Tara Murphy (U Sydney), Katherine Newton-McGee (U Sydney), Chris Phillips (ATNF), Roberto Ricci (ATNF), Elaine Sadler (U Sydney), Lister Staveley-Smith (UWA), Mark Walker (MAW Tech), Jasper Wall (UBC), Warwick Wilson (ATNF)

2. Outline Motivation Technology Observing strategy Catalog Content GPS candidates e-VLBI Data release Final words

3. Motivation for the AT20G survey No sensitive large area surveys above 5GHz Observation time drastically reduced by using new hardware Provide foreground subtraction for CMB missions Study high frequency source populations including high frequency GPS Image from Sadler et. al. - 2008MNRAS.385.1656S

4. WBAC 8GHz bandwidth 16 Channels 3 baselines 54ms sampling rate Simultaneous analog correlation No delay tracking 3 Telescopes 15°min -1 scan rate Observing at 20GHz Optic fiber data transport ATCA Image Credit: D.Smyth

5. Observing Strategy Delay tracking fixed on the meridian Telescopes scan N-S Sky rotates E-W Result is interleaving tracks across the sky Interleaves are stitched together to form maps

6. Candidate Sources Resulting maps still show a beam response, rms noise ~10mJy Candidates are selected above 40mJy

7. Confirmation Imaging observations at 20GHz to measure accurate flux/position o >80% confirmed as real sources Confirmed sources also observed at 5 and 8 GHz Sky coverage -90\deg < DEC < 0\deg Catalog contains 5700 sources above 40mJy at 20GHz AT20G 0054-3418

8. AT20G Catalog Content ~4000 sources have nearly simultaneous measurements Almost all extragalactic sources are AGN: 65% QSOs & BL Lacs 25% galaxies 10% faint/blank Nearly all are unresolved at 20GHz (<5’’) ~20% are GPS candidates (peaked or inverted) 11% 53% 13% 22% Inverted PeakedSteep Upturned

9. GPS Sample Selected to be peaked or inverted at 20GHz Avoided Galactic sources |b| < 2.5 843MHz from SUMSS 1.4GHz from NVSS 20 inverted sources observed at 40GHz and 95GHz with ATCA 106 Redshifts from 6dF, NED 38 Spectra observed at Siding Spring 2.3m telescope 10 VLBI observations 688 GPS sources with peaks above 5GHz

10. Z=0.066

11. Z=0.11

12. Z=0.60

13. Resulting Sources

14. Comparison to previous samples O’Dea SampleAT20G Sample Typical Peak1GHz8-15GHz Number of sources31688 Galaxy/QSO fraction50 / 5023 / 77 Median Z0.5 / 1.60.2 / 1.2 Median Log(P 5 )27 / 2825 / 27 O’Dea 1998 PASP, 110,493-532

15. e-VLBI

16. AT20G Data Release Sources above 500mJy are within the Bright Source Sample Full sample release is currently in preparation Website: www.atnf.csiro.au/research/AT20G/ First results from the ATCA 18GHz pilot survey, Ricci et al. 2004, MNRAS, 354, 305 The properties of extragalactic radio sources selected at 20GHz, Sadler et al. 2006 MNRAS 371, 898-914 The Australia Telescope 20 GHz (AT20G) Survey: The Bright Source Sample Massardi et al. 2008, MNRAS, 384, 774-802 The extragalactic radio-source population at 95GHz, Sadler et al. 2008 MNRAS 385, 1656

17. Conclusion / Final Words When the full sample release is complete it will open up a lot of new opportunities to study GPS (and CSS) sources 688 sources 144 redshifts 10 e-VLBI observations Future work: More redshifts More / Higher resolution e-VLBI measurements Better radio spectra