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PAST search for Reionization

PAST search for Reionization. Ue-Li Pen 彭威礼. Xiang-Ping Wu 武向平 , Jeff Peterson. Successes and Limitations in Cosmology. -CMB PS accuracy up to 1% -Cosmological parameters require low z normalization. -error bars on galaxy surveys: on small scales non-linear, stochastic, biased. 10%?

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PAST search for Reionization

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  1. PAST search for Reionization Ue-Li Pen 彭威礼 Xiang-Ping Wu 武向平, Jeff Peterson

  2. Successes and Limitations in Cosmology -CMB PS accuracy up to 1% -Cosmological parameters require low z normalization. -error bars on galaxy surveys: on small scales non-linear, stochastic, biased. 10%? -use only slope: on what scale? -on large scale, sample variance limited -use ‘best feel’ scale, error bar unknown. -must move to larger scales to get smaller errors. -are there other probes? WMAP: Spergel et al 2004

  3. Ending the Dark Ages • Z=6.3: Wyithe&Loeb, SDSS QSOs • Z=17: WMAP • Patchy, inhomogeneous? What scale? • Primary science goals of JWST, SKA • 3 current fast track experiments: PAST, LOFAR, MWA.

  4. Reionization • First objects: • 21cm @z>6 • 70-200 Mhz • ΔT = 23 mK, ~0.3 mJy • Angular scale 5’<Θ<20’, freq res500 khz z=10 simulation, Furlanetto et al, 2004

  5. Foreground: Galactic Synchrotron 408 MHz

  6. LOFAR

  7. Mileura Wide-angle Array Photos: Brian Corey and Eric Kratzenberg, MIT Haystack Observatory

  8. PAST Site

  9. PAST Strategy • Fast track to data: avoid custom design, off-the-shelf only. • Use existing TV technology, commodity PC’s for correlations • Learn as you build: fast turnaround, flexibility

  10. Antenna Design • Noise dominated by galaxy: Tgal=280 (150Mhz/f)2.5 K @ NCP • sensitivity: 104 m2effective area • Resolution: aperture synthesis，80 elements, 2km baselines • Receiver noise: NF < 2 dB (T<200K) • Pointing at north celestial pole, elevation 43o • Prototype: simple，fast。Currently 2 full working hexagonal pods

  11. Ulastai Urumqi150 km 42º 55’N86º 45’ E elev 2600m Ustir station Ground shield：15000ftmountains on all sides

  12. prototype E-W baseline 1123 m

  13. Mongolian Base

  14. Prototype maps 14h integration: many extragalactic sources Large FOV correction: implemented CMB adjoint projection S/N of 34, 38 for 3C061.1, 3C390.3 Predicted S/N: 36, 40 Correlator efficiency=0.1 (new board in development) Tsys=3000K (1/2 galaxy) 3C390.3 NCP 3C061.1 Compare to 8C 62-88 Mhz, 25o FOV

  15. Meteor reflections f t

  16. Ionosphere:Cass A Isoplanactic patch ~ 20km ~ 5o Phase distortions < 180o

  17. Antenna temperature 30 secrms No interference！ 8 h

  18. Comoving distances Low l anomaly: model primary CMB to l~20 CMB reionization ISW: lensing map predictions T-E correlations: can be predicted! PAST Pen 2003

  19. Potential Theoretical Benefits • Precision measurement of power spectrum at 10-8 accuracy (beyond PAST) • Dark energy dynamics: q0, a(t), ISW, dark matter dynamics/clustering (through lensing), gravity waves. • Initial conditions: 2nd order inflation effects, backreaction, curvature, etc. (through hydrogen matter P(k) and 3pcf).

  20. Challenges • Sensivity: >104 m2 • Man-made RFI：Ulastai appears quiet • Foregrounds: subtract continuum • Transients: Meteors, planes • Ionosphere: seems solvable • Processing: CMB techniques

  21. Outlook • October: 20 pods (2600 antennae), full u-v coverage • 80 pods: sensitivity for first detection • Goals: re-ionizing sources, lensing, cosmic acceleration, A-P test (Yu 2004)

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