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Ionized

Update: HI 21cm cosmic reionization experiments Chris Carilli (NRAO) MPIA July 2008 Last phase of cosmic evolution to be explored Bench-mark in cosmic structure formation indicating the first luminous structures GP + CMBpol => z ~ 7 to 11. Ionized. Neutral. Reionized.

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Ionized

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  1. Update: HI 21cm cosmic reionization experiments • Chris Carilli (NRAO) MPIA July 2008 • Last phase of cosmic evolution to be explored • Bench-mark in cosmic structure formation indicating the first luminous structures • GP + CMBpol => z ~ 7 to 11 Ionized Neutral Reionized

  2. HI 21cm Tomography of IGM: freq ~ 100 to 200 MHz Furlanetto, Zaldarriaga + 2004 z=12 9 • Large scale structure: , f(HI) , Temp (K, CMB, Spin) • Advantages: 3D, optically thin, dominant baryon component • Tomography requires SKA • TB(2’) = 10’s mK • SKA rms(100hr) = 4mK • LOFAR rms (1000hr) = 80mK 0.5Mpc 7.6

  3. Global (‘all sky’) reionization signature Signal ~ 20mK < 1e-4 sky Feedback in Galaxy formation No Feedback Possible higher z absorption signal via Lya coupling of Ts -- TK due to first luminous objects Furlanetto, Oh, Briggs 06

  4. Absorption LOFAR • 21cm forest • Radio GP SKA 10% Power spectra: 3D, 1dex in k 5Mpc QSO Cosmic Stromgren Spheres Signal ~ 0.5mJy rms(MWA) ~ 0.1mJy

  5. Pathfinders: 1% to 10% SKA 21CMA (China): 10,000 Dipole array working in Western China 2008 MWA (MIT/CfA/ANU) 32 Tile array deployment in WA 2009

  6. Challenge: Low frequency foreground – hot, confused sky Eberg 408 MHz Image (Haslam + 1982) 0.5 to 5.0 GHz • Coldest regions: T ~ 100 (/200 MHz)^-2.6 K • Highly ‘confused’: 1 source/deg^2 with S140 > 1 Jy • Synch. smooth ~ 100MHz vs. 21cm lines ~ 1 MHz

  7. Frequency differencing with MHz channels doesn’t work well for far-out sidelobes due to chromatic aberration. • Require < 0.2% calibration errors each day to reach thermal noise 1MHz separation Rphys ~ 1.7Mpc 10o Datta+ 09 5MHz separation 0.1% 1%

  8. Challenge: Interference 100 MHz z=13 200 MHz z=6 • Solutions -- RFI Mitigation (Ellingson06) • Digital filtering • Beam nulling • Real-time ‘reference beam’ • LOCATION! Aircraft Orbcom TV

  9. VLA-VHF: 180 – 200 MHz Prime focus X-dipole Greenhill, Blundell (SAO); Carilli, Perley (NRAO) Leverage: existing telescopes, IF, correlator, operations • $110K D+D/construction (CfA) • First light: Feb 16, 05 • Four element interferometry: May 05 • Detect CSS by Winter 06/07

  10. Project abandoned: Digital TV KNMD Ch 9 150W at 100km

  11. RFI mitigation: location, location location… 100 people km^-2 1 km^-2 0.01 km^-2 Chippendale & Beresford 2007

  12. Precisions Array to Probe the Epoch of Reionization (PAPER) PI Backer, Bradley Western Australian deployment in 2008 • Optimize for reionization PS/CSS • FoV ~ 30deg, short baselines < 0.6km • Staged engineering: GB06 8 stations  WA09 32 stations

  13. PAPER: Staged Engineering • Broad band sleeve dipole + flaps • FPGA-based ‘pocket correlator’ from Berkeley wireless lab • S/W Imaging, calibration, PS analysis: AIPY + Miriad/AIPS => Python + CASA, including ionospheric ‘peeling’ calibration 100MHz 200MHz Beam response BEE2: 5 FPGAs, 500 Gops/s

  14. PAPER/WA -- 4 Ant, July 2007 RMS ~ 1Jy; DNR ~ 1e4 CygA 1e4Jy Parsons et al. 2009 120MHz 180MHz

  15. Destination: Moon! • No interference • No ionosphere • Only place to study ‘dark ages’ RAE2 1973 • Recognized as top astronomy priority for NASA initiative to return Man to Moon (Livio 2007) • NASA concept study: DALI/LAMA (NRL + MIT + NRAO…) 10MHz

  16. J. Burns PI Colorado

  17. Challenge II: Ionospheric phase errors – varying e- content • TIDs – ‘fuzz-out’ sources • ‘Isoplanatic patch’ = few deg = few km • Phase variation proportional to ^2 • Solution: • Reionization requires only short baselines (< 1km) • Wide field ‘rubber screen’ phase self-calibration 15’ Virgo A VLA 74 MHz Lane + 02

  18. Say, its only a PAPER moon Sailing over a cardboard sea But it wouldn't be make-believe If you believed in me

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