Peter Wilkinson

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The SKA Design Study SKADS

• Peter Wilkinson
• University of Manchester
• JENAM Liege 6
  July 2005

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The SKA A revolution in Astronomy

• the next generation radio telescope for
  astronomy, STP,
• astroparticle physics fundamental physics
• 50-100 x sensitivity and gt105 times the survey
  speed
• of the currently most powerful radio
  interferometer
• Essential complement to ALMA, ELT, space
  observatories
• Coordinated internationally from outset
• In SKADS Europe is developing the
  breakthrough
• technologies for large multiple
  fields-of-view

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Why do we need a next generation radio
telescope?
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Radio band provides unique information

• From matter in different phases
• Penetrates dust/gas
• Cosmic magnetic fields
• Most accurate clocks
• Highest resolution images
• Access to the fundamental element via the 21cm
  line

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Radio telescopes make discoveries!

• Cosmic Microwave Background
• Quasars
• Cosmological evolution
• Gravitational lenses
• Superluminal motions
• Dark matter
• Masers
• Pulsars
• Gravitational radiation
• First extra-solar planetary system

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but whats so special about 106 m2 ?
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and in 21cm-line of hydrogen
The universe in starlight
Very different views -- but the hydrogen
signal is weak ! (Transition probability
for spin-flip about once per million years)

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SKAs sensitivity

• Detects normal galaxies out to cosmological
  redshifts
• (in HI and continuum)
• All objects detected in other wave bands likely
  to be detected and imaged with SKA
• Detects objects not visible in the optical!

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Science breadth is staggering!

• Five key projects
• Probing the Dark Ages, first black holes stars
• - epoch of reionization via HI at z 6 -15
• - star forming galaxies via CO at z 5 -15
• first AGN via deep continuum images
• Evolution of galaxies, dark matter, dark energy
• Exquisite power spectrum via HI galaxy surveys
• - Compute Universes equation of state
• Strength of Dark Energy as fn. of cosmic epoch
• Imaging the Cosmic Web in HI
• Kinematics and environment of galaxies from
• z5 to present via observations of neutral gas
  

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SKA science breadth is staggering!

• Extreme tests of General Relativity with pulsars
  and black holes
• - large surveys ? msec pulsar orbiting BH
• - pulsars orbiting close to SMBH in
  Galactic Centre
• - large surveys ? msec pulsar timing array
  for gravitational wave background
• The origin and evolution of cosmic magnetism
• - Rotation measures for 108 radio sources
• - Deep polarimetric observations of nearby
  galaxies clusters
• - Connection between magnetic fields and
  large-scale structure to zgt3
• The cradle of life searching for life and
  planets
• - J1-0 transitions of amino acids in
  molecular clouds
• - Terrestrial planet formation in
  circumstellar disks at 0.15 AU resolution
• - Leakage radiation from ETI transmitters
  out to 100s pc
• New discoveries to add those from 20th century
  radioastronomy
• ( see New Astronomy Reviews vol 48 December
  2004)

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Pulsars and GR
FUNDAMENTAL PHYSICS Pulsar black hole ?
Testing GR
to breaking point.
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Galaxy Evolution Cosmology
baryon wiggles as f(z) late universe result
of CMB fluctuations
HI redshift surveys of 109 galaxies (1000-
times larger than state-of-the-art) Test
Einsteins ideas for Dark Energy to
destruction.
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Epoch of Reionization

lower z
Evolution of hydrogen in the early universe as a
function of redshift (i.e. frequency of HI line)
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Needs technology breakthroughs

• An SKA covering a sub-set of the science goals
  could be built now for 5B using current
  technologies
• Challenge to reduce overall cost per m2 of
  collecting area to
• 1000/m2 (SKA cost target 1B)

?Take advantage of industrial RD in fibre optics
and electronics and computing for the
transport and handling of data

• Develop innovative new collector systems
  allowing larger fields-of-
• view for faster surveying

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The vision in Europe

• Electronic, phased array-based system
• Provide massive increase in flexibility and data
  gathering
• capability
• Configurable at observers will
• Provide a wide range of observing and processing
  
• options to maximise chance of new discoveries
  
• Dramatic paradigm shift for astronomy!

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The revolution in radio telescopes

• Based on phased arrays of
  receivers

Focal plane arrays (radio cameras)
Aperture arrays (solid state fish-eye lens cf.
shaped metal telescope)
MANY STEERABLE FIELDS-OF-VIEW !
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SKADS catalysed by FP6
8 EU countries 29 organisations
Netherlands coordinates
UK, France, Italy major
contributors
(Australia, South Africa, Canada, Russia) Main
deliverables establishing science/technical
specs optimisation
of Network architecture
breakthrough technology RD
large (100s m2) aperture array
EMBRACE all-digital
dual-pol phased array 2-PAD Scale of total
programme 38M EC
FP6 10.44M national funding 28M

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SKADS simulations will tell us

• What are the trade-offs between key design
  parameters (sensitivity, FOV etc) and key science
  ?
• number of FOV vs amount of physical area
• ( electronics vs metal concrete )
• May not need 106 m2 at all wavelengths !

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SKA poster (multi-beams)
Many beams offer great flexibility
Many targets/users
Interference rejection
SKADS prototype EMBRACE to be built in
Netherlands
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Small dish Smart feed

• Smart feed based on SKADS digital phased array
  2-PAD
• SKADS partners include
• Karoo Array Telescope
• (South Africa)
• xNTD array
• (Australia)

Two prototypes doing SKA-style science by 2009
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Network structures of the SKA

• Station model
• Fully distributed processing
• Upgrade via increasing Nb
• Modest data rates

• Totally flexible model
• Fully centralised processing
• Totally flexible
• High data rates

As computing power grows so will SKAs power
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Moores Law
1000 times more powerful computing even by 2020
? natural upgrade path to more beams ? more
powerful SKA with little change in hardware
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Summary

• SKA provides unique
• science

• Could be built now

• Cost is driving us to
• new technologies

Europe is leading the way via SKADS
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Timescales for the SKA

• Technology development phase to 2009
• - international selection of collector
  concept(s) and proceed to final design
• - selection of site short list 2006
  (Australia, South Africa, China, Argentina)
• Construction phases (2010 - 2020)
• - start with 10 pathfinder (central array)
• Estimated final cost 1 B is the aim
• 35 Europe
• 35 USA
• 30 Australia, Canada, China, India, Japan,
  South Africa,

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SKADS EC Framework 6 Design Study
Signal intensive
Receiving and Collector Concept, Station-level
Signal Conditioning and Processing Architecture
Control and monitor software
Wide Area Data transport Network
Data intensive
Data reduction and Imaging
Central Processor
Distribution and Archiving and Use by astronomer
Computing intensive Storage
intensive