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Vibrant New Field Overview: Explore Rapid Progress and Technical Developments in Radio Astronomy Search for 21cm Signal

This conference summary provides insight into the young and vibrant field of radio astronomy, discussing the rapid progress, technical developments, and significant impact on related sciences. It highlights key milestones such as the first maps and power spectra of HI at high redshifts, foreground subtraction techniques, and the challenges in detecting the 21cm signal. The text also covers observations from recent telescope missions, advancements in data processing techniques, and future instrument wish lists.

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Vibrant New Field Overview: Explore Rapid Progress and Technical Developments in Radio Astronomy Search for 21cm Signal

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  1. Conference SummaryUe-Li Pen

  2. Overview • Young, vibrant field! • Rapid progress: searching for needles in a haystack. • Lots of technical developments • Interest and impact in many related science fields • Possibly leading field in papers/data point • First maps and power spectra of HI at z>0.5

  3. 25 years ago: 21cm @ z=9 foreground subtraction. Bebbington 1986

  4. WSRT-LFFE Partial LOFAR

  5. First all sky 150 MHz map! Parsons et al, PAPER

  6. MWA 32 tiles (32T) 400m …5% prototype for 80-300 MHz Looking through a telescope on observing trip

  7. 32T Pipeline First Light 103 MHz • Observations from January 2010 • 3 x 7hr tracks with real-time calibration, peeling, imaging, resampling and averaging. • HEALPIX projection of Pic A field. • Pic A peeled to reveal many secondary sources. • Several simplifying assumptions relative to the 512T version, but all of the pieces are in place. 134 MHz 180 MHz 20°x 20° Zenith

  8. Robert C Byrd Telescope: 100m

  9. 760 MHz, z=0.87

  10. SVD foreground subtracted, frequency dependent beam corrected

  11. 100x rescaled: 100 μK 21cm signal

  12. Zadar Foreground Conference Polarized intensity all-sky surveys 1.4 GHz: DRAO (Wolleben et al., 2006) + Villa Elisa (Testori et al., 2008) 22.8 GHz WMAP (Page et al. 2007) depolarization Both surveys on absolute zero-level ! Low intrinsic percentage polarization outside of local features. APS analysis of 1.4 GHz survey (La Porta et al., 2006, 455, 9L ) + extrapolation  ~70 GHz optimal frequency to detect B-mode

  13. Wish list for future instrument • Stable: no moving parts • Stable: minimal active elements • Analysis: Whole sky small field of view • Symmetry: GBT is steerable: uniform maps. At 5x longer wavelength: E-W rotation invariance due to earth rotation. N-S rotation invariance if placed on aircraft carrier. • Compromise: wide N-S cylinders. Optical E-W FFT, digital N-S FFT, continuous frequency compensation, no mode mixing, no w-term!

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

  15. Summary of Summary • Vibrant new young field. • More opportunities for cross experiment interactions. • Many approaches and data sets under way! • “Understanding the galactic and extragalactic foregrounds”: first 1000x subtraction of foregrounds at 15’, 800MHz to reach 100 μK 21cm signal, with zero understanding.

  16. Special thanks • To Vibor and Marjan for organizing a great and successful conference!

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