Peter Wilkinson University of Manchester JENAM Liege 6 July 2005 The SKA Design Study “SKADS”

the next generation radio telescope for astronomy, STP, astroparticle physics & fundamental physics x sensitivity and >10 5 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 The SKA – A revolution in Astronomy

Why do we need a next generation radio telescope?

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

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

but what’s so special about 10 6 m 2 ?

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

SKA’s sensitivity SKA 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!

Science breadth is staggering! Five key projects Probing the Dark Ages, first black holes & stars - epoch of reionization: via HI at z = star forming galaxies: via CO at z = first AGN: via deep continuum images Evolution of galaxies, dark matter, dark energy - Exquisite power spectrum via HI galaxy surveys - Compute Universe’s equation of state - Strength of Dark Energy as fn. of cosmic epoch - Imaging the Cosmic Web in HI - Kinematics and environment of galaxies from z~5 to present via observations of neutral gas

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 10 8 radio sources - Deep polarimetric observations of nearby galaxies & clusters - Connection between magnetic fields and large-scale structure to z>3 The cradle of life – searching for life and planets - J=1-0 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 20 th century radioastronomy ( see New Astronomy Reviews vol 48 December 2004)

Pulsars and GR FUNDAMENTAL PHYSICS: Pulsar + black hole  Testing GR to breaking point.

Galaxy Evolution & Cosmology “baryon wiggles” as f(z) late universe result of CMB fluctuations HI redshift surveys of 10 9 galaxies (1000- times larger than state-of-the-art) Test Einstein’s ideas for Dark Energy to destruction.

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

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 m 2 of collecting area to ~€1000/m 2 (SKA cost target €1B)  Take advantage of industrial R&D 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

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

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 !

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 R&D : large (100s m 2 ) “aperture” array EMBRACE ; all-digital dual-pol phased array: 2-PAD Scale of total programme: ~€38M EC FP6: €10.44M; national funding ~€28M

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 10 6 m 2 at all wavelengths !

SKA poster (multi-beams) Many beams offer great flexibility Many targets/users Interference rejection SKADS prototype: “EMBRACE” to be built in Netherlands

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

Network structures of the SKA Station model Fully distributed processing Upgrade via increasing N b Modest data rates Station processor central processor Totally flexible model Fully centralised processing Totally flexible High data rates central processor As computing power grows – so will SKA’s power

Moore’s Law 1000 times more powerful computing even by 2020  natural upgrade path to more “beams”  more powerful SKA with little change in hardware

Cost is driving us to new technologies Could be built now SKA provides unique science International SKA access point: Summary Europe is leading the way via SKADS

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 (~ ): - 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, ……

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