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The Mission

The Mission. The Mission Explore the Dark Ages through the neutral hydrogen distribution Constrain the populations of the first stars and first black holes. Measure density fluctuations in the early universe Obtain the equation of state of dark energy test alternate theories of gravity

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The Mission

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  1. The Mission The Mission • Explore the Dark Ages through the neutral hydrogen distribution • Constrain the populations of the first stars and first black holes. • Measure density fluctuations in the early universe • Obtain the equation of state of dark energy • test alternate theories of gravity • [The first 4 slides are taken from Greg Taylor’s presentation on telescope requirements to LARC/DALI meeting at GSFC in Jan 2009]

  2. Assumptions Assumptions Array to be located on the Far Side of the Moon Minimizes terrestrial RFI Minimizes Ionospheric Fluctuations Observe during the Lunar night (50% duty cycle) Minimizes solar RFI Array to consist of N stations, each with M dipole pairs Each station will be capable for forming B beams on the sky Array assumed to be deployed in a locally flat region Array is to be deployed robotically 2

  3. Scientific Requirements Scientific requirements Redshift range: z=50 to 6 Angular resolution: 1.4’ Bandwidth: 8 MHz Sensitivity in 1000 h at z=15: 0.2 microJy/beam Brightness Sensitivity: 4 milliK FOV: 11 sq deg Dual Circular Dynamic range: 106 to 107 3

  4. Technical Requirements Technical requirements Frequency range: 30 - 200 MHz Collecting area: 3.0 km2 Maximum baseline: 10 km Bandwidth: 8 MHz Station Diameter: 150 m Number of Stations: 300 Number of Beams: 9 Dipole pairs in each station: 1500 Antenna FOV: 45 deg FWHM 4

  5. Ground-based reionization experiments

  6. Science Goals of the Murchison Widefield Array • Epoch of Reionization • Heliospheric Physics • Astronomical transients Sited in Western Australia MIT Haystack Observatory MIT Kavli Institute Harvard-Smithsonian Center for Astrophysics Australia National University Melbourne University + consortium Raman Research Institute Chippendale & Beresford 2007

  7. 32 antenna tiles Antenna tile Imaging by R. Wayth 26-tile MWA image Simulation

  8. Current Phase is MWA “Demonstrator” (under construction) N=512; D=4m - LARGE etendue; good foreground subtraction Digitized at antenna (660 Msamples/sec) - direct conversion Raw data rate = 512 X 2 X 660MHz X 10 bits = 844 GB/sec After digital filters and correlator: 20 GB/sec (32 MHz bandwidth; 2 Gvis per half-second) Real-time antenna and ionosphere calibration every 8 seconds Map of antenna tile field of view (~30 degrees across) every 8 seconds Status: 32 tiles on site; currently taking data with 26 tiles

  9. MWA power spectrum sensitivity (in principle) at redshift 8 Reionization spatial power spectrum Bowman, Morales & Hewitt (2006)

  10. C.Carilli, A. Datta (NRAO/SOC), J. Aguirre, D. Jacobs (U.Penn) • Focus: Reionization (power spec,CSS,abs) • Very wide field: 30deg

  11. PAPER: Staged Engineering • Broad band sleeve dipole + flaps • FPGA-based ‘pocket correlator’ from Berkeley wireless lab, routing via switch • S/W Imaging, calibration, PS analysis: AIPY, including ionospheric ‘peeling’ calibration, W projection… 200MHz 100MHz BEE2: 5 FPGAs, 500 Gops/s

  12. 150 MHz PWA-4/PGB-8 Powerspectrum

  13. Antenna Development for LUNAR (Bradley NRAO) • Optimize the electromagnetic behavior of the four-element helical array through parametric modeling. • Study effects of lunar deployment tolerances. • Develop a viable mechanical design for the low-mass, folding antenna truss structure. • Build prototypes for operation at 137 MHz and determine beam patterns by measuring the downlink power from a constellation of LEO satellites.

  14. LARC Concept of the Lunar Radio Array Notional design completed as part of NASA Award NNX08AM30G

  15. The Self-Tending Array Node and Communications Element -- STANCE -- Quad helical antennas, grounding cavity, and folding support truss adopted as the baseline design.

  16. NRAO Statement of Work: Software requirements Years 3 + 4: half-time postdoc position will be used to study the software requirements for the lunar array to detection the cosmological HI 21cm singal. Funding for the other-half time is being sought within the NRAO algorithms development group. Goals: Report on telescope software requirement, based on science requirements and design, summarizing processing and analysis software requirements. A report reviewing the current software being written for low frequency ground-based arrays, making recommendations as to aspects of these systems that can be incorporated into the Lunar software design. If time allows, explore low frequency data processing using data from existing low frequency instruments.

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