21 cm Reionization Forecast and Search at GMRTUe-Li Pen Tzu-Ching Chang Julia OdegovaJeff Peterson, CMUChris Hirata, Kris Sigurdson, Yashwant Gupta, Jayanta RoyRadiative Xfer simulation by Iliev, Mellema, Shapiro, Pen, et al

=0.09+/-0.03, zr=11WMAP 3yrUniverse at recombinationUniverse at reionization

ReionizationFirst objects: 21cm @ z=6-1590-200 MhzT ~ 20 mK, ~Jy- mJy (up to 1016 M of HI)Angular scale 5

Cosmic Reionization(Iliev, Mellema, Pen, Shapiro 2006)Largest radiative transfer cosmological reionization simulations: 1 degree FOV.Detection in 21cm hyperfine transition with radio telescopes. Structure on large scales (>20).See also Furlanetto, Oh, Zaldarriaga, Zahn, Morales, Mesinger, Croft, Ciardi, etclog10 T (mK)

Iliev et al, astro-ph/0702099

Iliev et al, Astro-ph/0702099

Foreground: Galactic SynchrotronHaslam 408 MHzMuch brighter than signal, but no spectral structure

Indian Giant Meterwave Radio Telescope30 dishes @45m ea.Operates in 2m bandCollaborators: Y. Gupta (chief scientist), Rajaram Nityananda (director), J. Roy, J. Peterson (CMU), C. Hirata (IAS), T. Chang (CITA), J. Odegova (Toronto), K. Sigurdson (UBC)

GMRT EoR Search

Operating telescope, 50,000m2 (geometric), up to 32 MHz BW, fully polarized, lowest band 100-200 MHz, sky limited. Currently biggest collecting area in this band.Half in central 1km core (relevant for EoR), rest in 20 km Y (useful for calibration).Previously reached RFI limit at 150 MHz after a few minutes of integration: power lines, TV stations, HAM amateurs, faulty home electronics. Software correlator: success of new RFI mitigation schemes, nearfield clean.Current effort invests 100 hours observing time per semester.

Step 1: new software correlator:imaging the full sky+horizon

Power Line NoiseTime-lag: Folded 70ms data on short baseline

Step 2: Phase calibrationReal time pulsar gated imaging calibrationPen et al 2007, GMRT internal report

Antenna based phase solutions

Fourier (u-v) map (Im)

Current StatusSensitivity forecasts for GMRT promisingRFI mitigation successful, physical elimination under investigation.Pulsar phase referencing successful.Polarization calibration and imaging achieved no non-pulsar sources found.Foreground subtraction under way. Frequency dependent primary beam: holographic pulsar beam mapping.

OutlookExisting constraints: optical depth from WMAP (Poln), SDSS QSOs.Theoretical progress: direct simulations indicate power on larger scales (>20), making detections more tractable.current: large data sets from GMRT, data analysis in progress. RFI problems solved: separate imaging of sky and RFI. Foreground subtraction main challenge.Bright outlook: several experiments underway to tap the next cosmic horizon: GMRT, LOFAR, MWA, Past/21CMA, Paper Exciting new window on universe for precision cosmology. Open field for theory and experiment.