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Cosmology using 21 cm emission

Cosmology using 21 cm emission. Jeff Peterson, CMU Talk 1…Update on early ionization telescopes (LOFAR, PAST, GMRT) Talk 2…Proposed Redshift survey. Telescopes with > 10,000 m^2 area that will be used in attempt to detect early (z~10) ionization. LOFAR PAST/21CMA GMRT.

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Cosmology using 21 cm emission

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  1. Cosmology using 21 cm emission Jeff Peterson, CMU • Talk 1…Update on early ionization telescopes (LOFAR, PAST, GMRT) • Talk 2…Proposed Redshift survey

  2. Telescopes with > 10,000 m^2 area that will be used in attempt to detect early (z~10) ionization LOFAR PAST/21CMA GMRT

  3. Simulated VHF sky images Furlanetto, et.al2003

  4. Extragalactic Foregrounds

  5. NETHERLANDS: LOFAR • 120-240 MHz • ~10,000 dipoles • Blue Gene correlator • Extensive outrigger network • 53 M euros • Operational 2007

  6. TEST ARRAYS “ITS”

  7. CHINA:The Primeval StructureTelescope,aka 21 CM Array

  8. W S N E 21CMA Layout

  9. Telescope Parameters • Rough Parameters • Total antennae 10,000 • Interferometer Elem. 81 • Effective area 20,000 m^2 • Sky temperature 200 K – 2000 K • Imaging field of view 100 sq deg • Angular resolution 5 arc minutes • Frequency Range 70 - 200 MHz • Redshift range 6 - 20 • Frequency resolution 20 kHz • Spatial resolution 6 Mpc • Mapping sensitivity 25 mK/sqrt(day) • Budget $3M • Operational 2006 280 antennae, on site, Ulastai June 2004 Over 2000 Installed, December 2004

  10. INDIA: The Giant Metrewave Radio Telescope 30 44 m dishes Currently hobbled by power line noise New PC based correlator summer 2006 Budget $200,000 plus exisitng GMRT

  11. Questions on Early Ionization

  12. 21 cm redshift survey to constrain dark energy • By Jeff Peterson and Ue-Li Pen • Use acoustic oscillations from z = 0 to z = 1.5 to detail the transition from deceleration to acceleration. • Survey 2 Pi steradians from 500 to 1500 MHZ with a 250,000 sq m fixed-pointed meridian-scan radio telescope. • Cylindrical reflectors allow for ultra-wide field observations, and inexpensive FFT based beam forming. • Modest cost--$20M--$0.02/redshift

  13. Baryon Wiggles Detected by SDSS and 2df

  14. Projected W and W’ sensitivity Blake and Glazebrook

  15. Dark Energy Constraint vs. redshift limit

  16. Local HI Luminosity Function Zwann et al at z=1.5 this is 2 microjansky We detect all these across 1/2 of sky in 6 months

  17. Four Cylinders each 2 km long • Line feeds at foci used to create 4000 beams N 2 km

  18. Cylindrical reflectors use suspended mesh, with a line of feed pointsReflector Cost: ~$20/m^2Survey Speed~A*N

  19. Darwin AUSTRALIA Brisbane Sydney Perth + Molonglo Adelaide Canberra Melbourne Hobart Existing cylinders MOLONGLO Cost:$12/m^2 (current dollars) OOTY Both rotate in one dimension

  20. Cylinder History • Popular 1960-1980 • Lost favor with advent of cryogenically cooled pre-amplifiers. • Room temp amplifiers with 20K noise temp now available. Illinois 400 ft Telescope ca. 1960

  21. Beam Former Signal Flow FFT vs t 4096 ADCs FFT vs x Transpose … FFT vs t FFT vs x

  22. 64 x 64 Processor Array One of 4096 RF signals 64 64

  23. Conclusions • Using off the shelf technology, a redshift survey telescope can be built for modest cost ($20M) which will yield 10^9 redshifts to z~1.5 • Will cover 100 times the SDSS volume • Will constrain W1 to ~0.1

  24. Subaru Deep Field z~6 Ly alpha

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