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Eric M. Wilcots University of Wisconsin-Madison
Eric M. Wilcots
University of Wisconsin-Madison
VLA/EVLA/VLBA (US)
ATCA (Australia)
DRAO (Canada)
WRST (Netherlands)
GMRT (India)
GBT (US) Arecibo (US) Parkes (Australia) Effelsberg
(Germany)
Improve continuum sensitivity by factors of 5 below 10 GHz and factors of 20 between 10 and 50 GHz
Continual frequency coverage between 1 and 50 GHz (maybe down to 300 MHz)
New correlator – up to 262,144 channels! Longer baselines – 0.004 arcsec at 50 GHz to
0.2 arcsec at 1 GHz (phase 2)
VLA EVLA Phase 1
EVLA Phase 2
Point source sensitivity
10μJy 0.8μJy 0.6μJy
bandwidth 0.1 GHz 8 GHz 8 GHz
# of channels
16 16,384 16,384
Freq. resolution
381 Hz 1 Hz 1 Hz
Angular resolution
0.”4 0.”4 0.”04
Extragalactic magnetic fields
Diffuse extragalactic synchrotron sources
13 cm (2.3 GHz) radar mapping of planets/moons
Mapping deep atmospheres of giant planets
H2CO in star forming regions
Extragalactic radio recombination lines
Imaging of thermal emission in star forming regions
“Cradle of Life” – formation and growth of planetary systems (terrestrial planets) terrestrial planet growth
“Strong-field Tests of Gravity” – pulsar and black hole physics pulsar/BH binaries
“Origin and Evolution of Cosmic Magnetism” –magnetic fields, anyone? all-sky RM survey with 20-30” separation between sources
“Galaxy Evolution and Cosmology” – cosmic star formation, HI surveys, Dark Energy Billion Galaxy HI Survey
“Epoch of Reionization” highly redshifted HI line
Frequency Range needed for SKA Science
ATA (Berkeley/SETI)
EVLA (Expanded VLA) – ongoing◦ Joint US/Mexico/Canada
◦ $200 million
◦ New Mexico
◦ In progress
KAT/MeerKAT (RSA)◦ In development
ASKAP (AUS)◦ In development
LOFAR (Netherlands)
LWA (US)
MWA (AUS/US)
FAST (China)◦ proposed
LOFAR (Netherlands)◦ In progress
◦ Construction phase to start this summer after critical systems design review
◦ 30-250 MHz
◦ Antenna stations spread over Netherlands, elsewhere in Europe
◦ EoR/high-z
MIT, CfA, ATNF, Aus. Universities, WA Overview
◦ 80-300 MHz (Low Freq. Demonstrator) 8000 dipole antennas Static FoV ~ 25 degrees (150 MHz) Redshifted 21 cm, heliosphere, transient radio sky ~$10M
◦ 800-1600 MHz (xNTD) 3500 sq m (20 x 15m dishes) Tsys ~ 50 K 256 MHz instantaneous bandwidth 30 independent beams 30 sq degree FoV HI, continuum surveys
NRL, Los Alamos, UNM, UT-Austin
Overview◦ 10-88 MHz
◦ Dipole technology
◦ Baslines 50600 m, resolution ~10”
◦ Collecting area ~106 m2
Aperture 3535 m2
Tsys 55 K Uncooled
Freq 700-1750 MHz
Bandwidth 512 MHz
Channels 65536
Max baseline 1500 m 35” resolution
FoV 5.1 deg2 Feed array
Funding/Timeline◦ $42M (KAT) + $70M (MeerKAT) from DST◦ $24M site infrastructure establishment◦ $1.7M “human capital development” Research chairs (UCT/UWC)
Postdoctoral fellowships
Student bursaries
◦ $4.3M operations/management
◦ 1st seven antennas 2009
Timeline: KAT Big KAT (450 antennas)
ASKAP, 700-1800 MHz, with strawman 30 12m dishes with PAF, upgrade/expansion to 45.
5-sigma detectionsfor all southern-hemisphere, “shallow” (1 yr) surveystrawman, expansion FOV 30 deg2 – depends on success of PAF technology -N=600,000
Johnston et al. 2007
Similar simulationfor a deep (1 yr)single pointing,N= 100,000
Johnston et al. 2007
Frequency Range: 100 MHz – 25 GHz Instantaneous BW: 25% of central freq. Configuration: bmin = 20m, 20% of
collecting area within 1km, 50% within 5 km, 75% within 150 km, bmax=3000 km (angular resolution < 0.02 / f (GHz) arcsec)
FoV: 1 sq deg2 (1.4 GHz), 200 sq deg2 (700 MHz)
Sensitivity 50 times the EVLA
US◦ LNSD (Large N/Small D) design◦ ~4200 12m dishes
Canada◦ LAR (Large Adaptive Reflector)◦ Receiver package suspended over collecting area
Europe◦ Tiles/cylinders
Australia◦ Spherical lens
India◦ 25m dishes
China◦ Multiple Arecibos
Inner core
Station
Reference Design
Wide-angle radio camera +
radio “fish-eye lens”
Site Selection 2008/2009◦ Western Australia & South Africa are the two
finalists
Final Specs 2008/2009
System Design 2008-2012
Phase 1 Construction (10%) 2012-2015
Redshifted HI
SKA Survey Metric
SKA/ALMA
Epoch of Reionization
Does the LX-L1.4GHz correlation extend to lower mass systems (i.e. galaxy groups)?
Full census of Galactic Pulsars – 10,000 pulsars◦ 10% will be ms pulsars
◦ 1% will be relativistic binaries tests of strong field general relativity
Detection of Crab-like pulsars in the Local Volume probe the IGM in the local Universe
Cosmic Magnetism via RM Survey
SKA could play Unique Role in Disk Studies
• SKA will have best resolution/sensitivity for thermal
emission (20 GHz)
• For direct detection of structure in disks induced by
planets, sub-AU resolution is key.
•High angular resolution probes terrestrial planet region
and enables following evolution over orbital timescales.
•Short centimeter wavelengths are critical for tracking
grain growth from sub-micron interstellar size particles
to “pebbles”.Bate et al. 2003
“As we know, there are known knowns. There are things we know we know. We
also know there are known unknowns. That is to say we know there are some things we do not know. But there are also unknown uknowns, the ones we
don’t know we don’t know.”Someone Famous
SKA Director: Richard Schilizzi (Netherlands)
Project engineer: Peter Hall (Australia)
SKA Engineering and Science Working Groups
Separate international consortia in Europe, South Africa, Australia, US
Cornell – Lead Institution MIT/Haystack NRL Virginia Tech Wisconsin Illinois NRAO Cal Tech/JPL Berkeley/SETI Institute
Cornell et al submitted Technology Development Project (TDP) to NSF in January◦ Demonstrators/costing
Did not submit a site selection proposal…. Limited (no?) funding available Gearing up for the Decadal Survey
Technology Demonstration◦ Can focal plane arrays actually work on a large
scale?◦ Software/data transport◦ Wide-band receivers◦ Cryogenics on a large scale
Science◦ Evolving science case
Money…..◦ This ain’t cheap $1.5B
◦ Europeans (~$50M), Australians (~$35M), South Africans (~$200M) have all started spending real money
◦ US…..
