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Judd D. Bowman Arizona State University Alan Rogers MIT/Haystack Observatory May 26, 2011

Experiment to Detect the Global EoR Signature (EDGES). Judd D. Bowman Arizona State University Alan Rogers MIT/Haystack Observatory May 26, 2011. Outline. Brief motivation Instrument Overview Results Reionization Galactic synchrotron spectral index Radio Frequency Interference

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Judd D. Bowman Arizona State University Alan Rogers MIT/Haystack Observatory May 26, 2011

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  1. Experiment to Detect the Global EoR Signature (EDGES) Judd D. Bowman Arizona State University Alan Rogers MIT/Haystack Observatory May 26, 2011

  2. Outline • Brief motivation • Instrument Overview • Results • Reionization • Galactic synchrotron spectral index • Radio Frequency Interference • Looking ahead

  3. The global 21 cm signal Pritchard & Loeb (2011)

  4. EDGES

  5. EDGES – Experiment to Detect the Global EoR Signature Murchison Radio-astronomy Observatory (MRO), Western Australia CSIRO support trailer Antenna

  6. in from antenna 2nd stage amp LNA calibration source switch to digitizer dithering noise source to 2nd stage

  7. Technical challenges • Cannot (easily) create external calibrator, difficult matching sky temperature across band • Cannot fully characterize antenna in lab • Beam pattern changes with frequency • Antenna and LNA impedance change with frequency, in general poor match • Receiver noise reflections • Multi-path reflections • Non-linear effects prevent ideal comparison-switch calibration

  8. EDGES measured spectrum Murchison Radio-astronomy Observatory (MRO) Aug 20 – Oct 20, 2009 1440 wall-clock hours on sky 500 hours after RFI cuts 50 hours eff. integration +15 dB Bowman & Rogers (Nature, 2010)

  9. EDGES parameter estimation #1: 21 cm reionization model #2: Foreground model Pritchard & Loeb (2010, submitted) 2 science parameters: z and zr 4-19 nuisance parameters: an (ACKK!!)

  10. EDGES lower limit on duration zr > 0.06 for 6 < zr < 13 (95% confidence) Bowman & Rogers (Nature, 2010)

  11. EDGES absolute calibration Tgal = 237  10 K (3 sigma) @ 150 MHz 100-200 MHz:  = 2.5  0.1 (3 sigma) 150-408 MHz:  = 2.52  0.04 (3 sigma) Rogers & Bowman 2008

  12. Integrated RFI(time excision only – by broadband power level in FM, Orbcomm, DTV bands: 30% removal) Note: shows every channel that ever had RFI over 3 months

  13. Orbcomm LEO satellite constellation

  14. Outline • Brief motivation • Instrument Overview • Results • Galactic synchrotron spectral index • Reionization • Radio Frequency Interference • Looking ahead

  15. EDGES reionization forecast Pritchard & Loeb (2010)

  16. EDGES reionization forecast Morandi & Barkana (2011)

  17. Physical model templates Data deviates from power law primarily due to the antenna mismatch factor 1 - |G|2 EOR absorption x 104 AEER

  18. Summary • Identified key technical challenges and viable approaches • See AEER talk tomorrow morning • CoRE (RRI), Bighorns (Curtin University), DARE (U. Colorado), LWA cosmic dawn, Peterson • Beginning to rule out rapid reionization histories • z>0.06 between 6<z<13 • First reionization science from any redshifted 21 cm experiment • Ancillary science and supporting measurements • Galactic synchrotron spectral index • Deepest broadband spectrum ever acquired at 5 mKrms • RFI properties of remote sites in US and Australia (more to come) • More compelling 21 cm science in the near future • Constrain derivative of neutral fraction for generic reionization histories • Attempt first detection of z=15-25 absorption feature to probe UV emission from first stars and early IGM heating

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