Dark Energy BAO Intensity Mapping

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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

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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 . - PowerPoint PPT Presentation

Transcript of Dark Energy BAO Intensity Mapping

Page 1: Dark Energy BAO  Intensity  Mapping

Dark Energy BAO Intensity Mapping

T. Chang, UP, J. Peterson, P. McDonaldPRL 100, 091303 (March 5, 2008)

UP, L. Staveley-Smith, J. Peterson, T. Chang arXiv:0802.3239

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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)

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Present LSS BAO Detections

• Percival et al 2007

Percival et al 2007Eisenstein et al 2005

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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)

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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).

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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

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Pen et al 2008

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Prospects with existing telescopes

• Cross correlation detected with µK noise.• CMB-like scan strategy for extended source mapping.• Parkes multibeam: 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.

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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)

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Existing cylinders

MOLONGLO

OOTY

Molonglo

AUSTRALIABrisbane

Darwin

PerthCanberra

Hobart

AdelaideMelbourne

Sydney

+

NORTHERN CROSS

Cambridge

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

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Mapping LSS

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Cosmic Variance Limited Hubble SurveysChang, UP, Peterson, McDonald, PRL 100, 091303, March 5, 2008

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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.