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21CMA

21CMA. 21 Centimeter Array a.k.a. PAST. Reionization. 21cm: hyperfine transition of neutral Hydrogen. 21CMA a.k.a. PAST. B asic ideas:. an experiment, not an observatory use cheap, off-the -shelf technology (i.e. TV+PC) simple design (looking at NCP)

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21CMA

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  1. 21CMA 21 Centimeter Array a.k.a. PAST

  2. Reionization 21cm: hyperfine transition of neutral Hydrogen

  3. 21CMA a.k.a. PAST Basic ideas: • an experiment, not an observatory • use cheap, off-the -shelf technology (i.e. TV+PC) • simple design (looking at NCP) • choose site with minimal EM interference • to become operational before MWA/LOFAR Xiang-Ping Wu (NAOC) Ue-Li Pen (CITA) Jeff Peterson (Carnegie)

  4. Map of 21CMA site VLBI 21CMA

  5. Ulastai Urumuqi N E

  6. Log-Periodic antenna

  7. A pod (127 antenna) 20m

  8. 21CMA data collection system Optical transmitter Optical receiver array LNA filter amplifier Opt. fibre ADC correlator

  9. Basic Design of 21CMRA At z=9, 10 comoving Mpc  ~ 0.6 MHz,  ~ 3.6 arcmin frequency range 70-200 MHz (6.1<z<19.3) baseline: 2 km, (at 140 MHz, 3.6 arcmin) Collecting Area 104 m2 A/L2 ~ 0.01

  10. Schedule & Status • summer 2003 Ue-Li, Jeff, Xiang-Ping discussed the idea • autumn 2003 site search began, Ulastai chosen • March 2004 7-antennae prototype, first image • August 2004 array design finished • January 2005 batch I (first 20 pods) constructed • summer 2005 batch II (60 pods) construction, data • collecting electronics installation • January 2006 fully operational Total cost estimate: 15-30 M yuan, now borrowing from other groups in NAOC, will apply a grant, please support!

  11. January 1, 2005

  12. 3CR390.3 NCP 3CR061.1 First skymap (dirty) 3C061.1

  13. Dark Energy? • AP test • power spectrum measurement • lensing • ...

  14. Discussion on dark energy observation

  15. Observation Data Dark Energy? Theoretical Assumptions General Relativity Cosmo Principle Model III ModelI Model II

  16. Ways to measure dark energy • Gravitational test: • luminosity distance • angular diameter distance • growth of perturbation • solar system & beyond • Non-Gravitational test: • variation of constants • dark energy interaction • supernovae & GRB • gravitational lensing • cluster • large scale structure • CMB • 21cm • gravitational wave • micro-gravity, solar system & lab

  17. What can we do in China Existing projects: LAMOST, 21CMA New Projects: ?

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