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

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: 10 6 to 10 7

4 Technical Requirements  Technical requirements  Frequency range: MHz  Collecting area: 3.0 km 2  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

Ground-based reionization experiments

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

Antenna tile 32 antenna tiles 26-tile MWA imageSimulation Imaging by R. Wayth

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

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

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

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… 100MHz 200MHz BEE2: 5 FPGAs, 500 Gops/s

150 MHz PWA-4/PGB-8 Powerspectrum

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.

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

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

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: 1.Report on telescope software requirement, based on science requirements and design, summarizing processing and analysis software requirements. 2.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. 3.If time allows, explore low frequency data processing using data from existing low frequency instruments.