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Dark Energy BAO Intensity Mapping

Dark Energy BAO Intensity Mapping. T. Chang, UP, J. Peterson, P. McDonald PRL 100, 091303 (March 5, 2008) UP, L. Staveley -Smith, J. Peterson, T. Chang arXiv:0802.3239. Baryon Acoustic Oscillations – Dark Energy Probe. CMB acoustic oscillations: imprinted standard ruler, 100 Mpc .

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Dark Energy BAO Intensity Mapping

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  1. Dark Energy BAO Intensity Mapping T. Chang, UP, J. Peterson, P. McDonald PRL 100, 091303 (March 5, 2008) UP, L. Staveley-Smith, J. Peterson, T. Chang arXiv:0802.3239

  2. Baryon Acoustic Oscillations – Dark Energy Probe • CMB acoustic oscillations: imprinted standard ruler, 100 Mpc. • Present in current matter distribution WMAP5 and other, Nolta et al (2008)

  3. Present LSS BAO Detections Percival et al 2007 • Percival et al2007 Eisenstein et al 2005

  4. Mapping Large Scale Structure • Measure individual galaxy redshifts – SDSS(3), SKA, ADEPT, WFMOS (radio/optical), etc. • OR measure collective emission from galaxies without resolving individual objects. Hundreds of galaxies in each BAO pixel! • Prototype observations and analysis in progress – CMU cylinder, GBT, VLBA, ATA, Parkes, GMRT. (Bandura, Staveley-Smith, Briggs)

  5. Radio Mapping Experiments • Redshifted 21cm Hydrogen transition: 300MHz-1.4 GHz, radio maps • Large area survey, large field of view, low surface brightness: like CMB. Signal ~ 50 µK • Foregrounds large -- ~K, but smooth (spatially and spectrally).

  6. First Intensity Mapping Detection • Archival analysis of Parkes HIPASS data • 21cm Survey of 68% of the sky, at dec<22 deg • z<0.04, median detected galaxy z=0.01 • Cross correlate with 6dF

  7. Pen et al 2008

  8. Prospects with existing telescopes • Cross correlation detected with µK noise. • CMB-like scan strategy for extended source mapping. • Parkesmultibeam: perfect for all sky z<0.13 (receiver limit). Redo SDSS volume, fill in zone of avoidance (?). Strengthen low z BAO signal. • GBT: pencil beam surveys to z=2.5, in progress (April 23-May 1, 2008). May detect BAO at z=1.5 with major campaign. • ATA (used as single dishes): northern sky, z<0.2.

  9. Dedicated Survey Experiment • Low frequency technology cheap, modest collecting area • Large field of view: receiver arrays • High surface brightness sensitivity: compact arrays • Stable, reliable: no moving parts • Technologies: aperture arrays (Wyithe, Loeb, Geil 2008), cylinders (Peterson et al)

  10. Darwin AUSTRALIA Brisbane Sydney Perth + Molonglo Adelaide Canberra Melbourne Hobart Existing cylinders NORTHERN CROSS MOLONGLO Cambridge OOTY

  11. CMU cylinder under construction: U. Seljak, J. Peterson, K. Bandura.

  12. Mapping LSS

  13. Cosmic Variance Limited Hubble Surveys Chang, UP, Peterson, McDonald, PRL 100, 091303, March 5, 2008

  14. Conclusions • Baryon Acoustic Oscillations – geometric measure of the universe and dark energy • First detections reported – 2dF, SDSS • Intensity Mapping: unresolved galaxies. • First detection of IM through cross correlation in archival HIPASS data. • Prototypes and observations under way. Cylinder telescopes a promising technology.

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