The Mission

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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 Taylors
  presentation on telescope requirements to
  LARC/DALI meeting at GSFC in Jan 2009

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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

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Scientific Requirements

• Scientific requirements
• Redshift range z50 to 6
• Angular resolution 1.4
• Bandwidth 8 MHz
• Sensitivity in 1000 h at z15
• 0.2 microJy/beam
• Brightness Sensitivity 4 milliK
• FOV 11 sq deg
• Dual Circular
• Dynamic range 106 to 107

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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

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Ground-based reionization experiments
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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
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32 antenna tiles
Antenna tile
Imaging by R. Wayth
26-tile MWA image
Simulation
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Current Phase is MWA Demonstrator (under
construction)
N512 D4m - 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
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MWA power spectrum sensitivity (in principle) at
redshift 8
Reionization spatial power spectrum
Bowman, Morales Hewitt (2006)
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C.Carilli, A. Datta (NRAO/SOC), J. Aguirre, D.
Jacobs (U.Penn)

• Focus Reionization (power spec,CSS,abs)
• Very wide field 30deg

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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
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150 MHz PWA-4/PGB-8
Powerspectrum
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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.

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LARC Concept of the Lunar Radio Array
Notional design completed as part of NASA Award
NNX08AM30G
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The Self-Tending Array Node and Communications
Element
-- STANCE --
Quad helical antennas, grounding cavity, and
folding support truss adopted as the baseline
design.
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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.