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

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Presentation on theme: "Cosmology using 21 cm emission Jeff Peterson, CMU Talk 1…Update on early ionization telescopes (LOFAR, PAST, GMRT) Talk 2…Proposed Redshift survey."— Presentation transcript:

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

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4 Simulated VHF sky images Furlanetto, et.al2003

5 Extragalactic Foregrounds

6 NETHERLANDS: LOFAR MHz ~10,000 dipoles Blue Gene correlator Extensive outrigger network 53 M euros Operational 2007

7 TEST ARRAYS “ITS”

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9 CHINA:The Primeval StructureTelescope, aka 21 CM Array

10 E W SN 21CMA Layout

11 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 MHz Redshift range Frequency resolution 20 kHz Spatial resolution 6 Mpc Mapping sensitivity 25 mK/sqrt(day) Budget $3M Operational antennae, on site, Ulastai June 2004 Over 2000 Installed, December 2004

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

14 Questions on Early Ionization

15 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

16 Baryon Wiggles Detected by SDSS and 2df

17 Projected W and W’ sensitivity Blake and Glazebrook

18 Dark Energy Constraint vs. redshift limit

19 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

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

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

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

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

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

25 64 x 64 Processor Array 64 One of 4096 RF signals

26 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

27 Subaru Deep Field z~6 Ly alpha


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