The Square Kilometre Array

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The Square Kilometre Array

• Richard Schilizzi
• International SKA Project Office
• www.skatelescope.org
• IAU Genaral Assembly, Prague, 16 August 2006

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outline

• Telescope parameters
• Science drivers
• Reference Design
• SKA pathfinders development of Reference Design
  technology
• Site selection
• SKA governance
• Timeline

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The Square Kilometre Array

• A radio telescope with
• sensitivity to detect and image hydrogen in the
  early universe ? very large collecting area
• Central concentration of the collecting area for
  optimal detection of hydrogen, pulsars, and
  magnetic fields
• fast surveying capability over the whole sky
  ? very large
  angle field of view
• capability for detailed imaging of compact
  objects like active galactic nuclei ? large
  physical extent

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Square Kilometre Array

• 1 km2 collecting area in an interferometer
  array
  sensitivity 50 x Expanded VLA
  
  survey speed gt10000 x faster than EVLA
• frequency range 0.1 0.3 GHz (EoR array)
  0.3
  3 GHz (mid-band)
  3 25 GHz (hi-band)
  
• configuration
  longest
  baselines gt3000 km 50 collecting arealt5km
• wide field of view 50 sq. degree at lt1 GHz
• target construction cost 1 billion
  operating
  costs 100 million /year
• Target first science (10SKA) 2014 completion
  date 2020

VLA
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sensitivity and survey speed
continuum sensitivity
survey speed
Cordes et al
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SKA Key Science Drivers

• Probing the Dark Ages
• When how were the first stars formed?
• Cosmology and Galaxy Evolution
• Galaxies, Dark Energy and Dark Matter
• Strong-field tests of General Relativity
• Was Einstein correct?
• Origin Evolution of Cosmic Magnetism
• Where does magnetism come from?
• Cradle of Life
• What and where are the conditions for life?

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SKA science book
Science with the Square Kilometre Array
eds C.Carilli, S.Rawlings, New Astronomy
Reviews, Vol.48, Elsevier, Dec. 2004
www.skatelescope.org
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Probing the Dark Ages
COSMIC HISTORY OF THE UNIVERSE
The Dark Ages Era of the Universe from 300 000 -
1 000 000 000 yr after the Big Bang during which
the first stars and galaxies formed Epoch of
Reionization 14 lt z lt 6 HI signature 90 ?
200 MHz
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Probing the Dark Ages
Global signal (CoRE, PAPER)
Statistical detection of fluctuations LOFAR, MWA,
PAST
Direct detection of structure - Needs full SKA
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Probing the Dark Ages
SKA Role Detect and image hydrogen in the neutral
IGM - shed light on the process of re-ionization
and physics of formation of the
first luminous objects in the Universe
z
Furlanetto
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The Nature of Dark Energy
Blake and Rawlings
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The Nature of Dark Energy
SKA Role 1) Hemisphere survey to locate and
measure spatial distribution of 109 galaxies to
z1.5 via their hydrogen emission and
spectroscopic redshifts
(3.5 HYDROGEN)
Blake, Rawlings et al
3) Hubble constant via water masers
2) Measure patterns in the cosmic shear
distortion caused by weak lensing in the radio
sky
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Strong field tests of gravity Was Einstein
Right?
Pulsars Collapsed stars with extreme physical
properties
Most accurate clocks known 10-9sec
High Gravity Field 2x105 xSun
Pulsars Cosmic Lighthouses
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Strong field tests of gravity
SKA role Identify and time pulsars with
nano-second accuracy
Clocks
Gravity
Sensitive gravity wave detector
Test GR around Black Holes
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Gravitational wave detection
Ensemble of milli-sec pulsars
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SKA will find 20000 pulsars in our Galaxy
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The Origin of Cosmic Magnetism
Magnetic Fields role in star formation?

• Magnetic fields are crucial in
• galaxy star formation
• turbulence gas motions
• acceleration propagation of cosmic rays
• But what is their origin, evolution and
  structure?
• top-down or bottom-up process
• exotic origin (phase transitions, strings)?
• standard plasma physics (turbulence,
  instabilities)
• is there a connection between magnetic field
  formation and structure formation in the early
  universe

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The Origin of Cosmic Magnetism

• Radio observations provide a
  unique probe of cosmic magnetic
  field and orientation
• Synchrotron emission, Polarization,
  Rotation Measures
• SKA will provide first detailed 3D
  picture of cosmic magnetic field
• Polarization studies of gt107 sources
• RM grid
• 10000 x improvement

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The Cradle of Life

• Probe conditions for life in our Galaxy
• Image proto-planetary disks in nearby stars
• Search for Extraterrestial Intelligence
  (full details in
  Jill Tarters Invited Discourse
  this evening)

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The Cradle of Life
SKA Role Study proto-planetary disks in formation
milliarcsec resolution
cm??
Theoretical Simulation
Probe the Habitable zone in disks
Composition of building blocks of disks -
pebbles to boulders
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The Cradle of Life
The Search for Extraterrestial Intelligence Airpo
rt radars _at_ 100 l.y. 500 stars Ionospheric radar
_at_5000 l.y. 600 000 000 stars
SKA 1000-fold improvement
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Exploration of the Unknown
Discovery of first pulsar

• Unplanned discoveries
• Pulsars
• Microwave Background
• Cosmic Evolution
• Dark Matter in galaxies
• Quasars
• Jets Superluminal motion

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Exploration of the Unknown
transients

• Design Strategies
• Flexibility
• Area, Field-of-view
• Time resolution buffering
• Frequency coverage
• Upgradability
• Multiple simultaneous use

Cordes et al
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SKA technology a global collaboration

• 10-year development so far
• Preliminary system design underway
• 1 SKA pathfinders now under construction in
  Australia (xNTD, MWA), South Africa (KAT),
  Netherlands (LOFAR), and USA (ATA). Timescale
  2004-2010
• Role of industry IT, data transport, HPC, mass
  manufacturing

Other engineering development from MWA, LWA,
EVLA, EVN, e-MERLIN, and DSN
LOFAR
KAT
xNTD
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Reference Design
Central 5 km
All-sky monitor
Not to scale
gt3000 km
digital radio camera
Radio camera
Station
SKA will be built out from the centre First 10
(phase 1) will have max baselines 50 km
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Reference Design Technology

• Small dishes
• ATA (USA) xNTD (Australia) KAT (South
  Africa) Canada India DSN Array
  

wide-band feed
Allen Telescope Array
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Reference Design Technology Phased arrays
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Reference Design Technology

• Long distance data transport over fibre
• EVN /JIVE e-MERLIN
• High speed data processing
• ATA EVLA xNTD KAT
  LOFAR

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Site selection

• Physical characteristics required
• Very quiet radio frequency environment,
  particularly for the core region
• Large physical extent (gt3000 km)
• Low ionospheric turbulence
• Low troposphere turbulence

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Site selection
Big city population several
million
Small town population several
thousand
Candidate SKA core location population a
few
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Site selection

• Physical characteristics required
• Very quiet radio frequency environment,
  particularly for the core region
• Large physical extent (gt3000 km)
• Low ionospheric turbulence
• Low troposphere turbulence
• Not many suitable sites in the world
• Site selection process started in 2003
• Request for full proposals issued 1 September
  2004
• Four proposals received on 31 December 2005
• Short-list of acceptable sites 31 August 2006

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Argentina Brazil
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Australia NZ
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China
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South Africa 7 countries
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Current SKA governance
gt50 institutes in 17 countries actively involved
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SKA timeline
1 SKA Science
Inter-governmental discussions including site
selection
Initial concept
10 SKA Science
First SKA Working Group
Site short-listing
ISSC MoAs
Science Case published
SKA Complete




2000
92 96 04 05 06 07 08 09 10 14 18 22

2000


Feasibility study
Full array Build 100 SKA
Phase 1 Build 10 SKA
Concept exposition
SKA System Design
Optimise Design
Reference design selected
Construct 1 SKA Pathfinders
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Summary of the project status

• Science case published
• Engineering studies published
• Reference Design identified
• Coherent portfolio of technologies under
  development through funding of SKA pathfinder
  telescopes
• Preliminary system design in progress
• Site selection in progress

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• www.skatelescope.org