Conference Summary Ue-Li Pen

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

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

WSRT-LFFE Partial LOFAR

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

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

32T Pipeline First Light 20°x 20° Zenith 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

Robert C Byrd Telescope: 100m

760 MHz, z=0.87

SVD foreground subtracted, frequency dependent beam corrected

100x rescaled: 100 μK 21cm signal

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 W. Reich Zadar Foreground Conference

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!

CMU cylinder under construction: U. Seljak, J. Peterson, K. Bandura, K. Sigurdson 19

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.

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