Ionized Neutral Reionized 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

HI 21cm Tomography of IGM: freq ~ 100 to 200 MHz z= Large scale structure:  f(HI), Temp (K, CMB, Spin) Advantages: 3D, optically thin, dominant baryon component Tomography requires SKA   T B (2’) = 10’s mK  SKA rms(100hr) = 4mK  LOFAR rms (1000hr) = 80mK Furlanetto, Zaldarriaga Mpc

Global (‘all sky’) reionization signature Signal ~ 20mK < 1e-4 sky Possible higher z absorption signal via Lya coupling of T s -- T K due to first luminous objects Feedback in Galaxy formation No Feedback Furlanetto, Oh, Briggs 06

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

Pathfinders: 1% to 10% SKA MWA (MIT/CfA/ANU) 32 Tile array deployment in WA CMA (China): 10,000 Dipole array working in Western China 2008 SiteTypeFreq MHzArea m 2 GoalDate GMRTIndiaParabola e4CSS CMAChinaDipole e5PS2008 PAPERGB/Oz/SA?Dipole e3PS/CSS2009 MWAdemoOzAperture array e4PS/CSS2009 LOFARNLAperture array e5PS/CSS2010

Challenge: Low frequency foreground – hot, confused sky Eberg 408 MHz Image (Haslam ) Coldest regions: T ~ 100  z)^-2.6 K Highly ‘confused’: 1 source/deg^2 with S 140 > 1 Jy Synch. smooth ~ 100MHz vs. 21cm lines ~ 1 MHz 0.5 to 5.0 GHz

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 R phys ~ 1.7Mpc 5MHz separation 10 o Datta %1%

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

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

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

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

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

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 100MHz200MHz BEE2: 5 FPGAs, 500 Gops/s Beam response

CygA 1e4Jy PAPER/WA -- 4 Ant, July 2007 RMS ~ 1Jy; DNR ~ 1e4 Parsons et al MHz180MHz

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

J. Burns PI Colorado

 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 Challenge II: Ionospheric phase errors – varying e- content Virgo A VLA 74 MHz Lane ’

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