Future Array Design & Technology Tony Beasley (NRAO)

Fifteenth Synthesis Imaging Workshop 1-8 June 2016 Future Array Design & Technology

• Short history of radio astronomy • Review of current/planned telescopes • Leading-edge technologies Electromagnetic Radiation

• Varying physical properties – temperature, pressure, structure, magnetic fields yield different EM emissions • Radio – non-thermal acceleration of charged particles, spiraling in magnetic field, thermal emission • Atoms & molecules – also possess unique radio frequencies Heinrich Hertz: 1888 – early radio transmission Radio Emission from Sun? Edison (1890), Lodge (1897) ….

Wilsing & Scheiner 1896

Nordman 1900 • All unsuccessful at e.g. detecting Sun… • Planck – estimates Solar thermal radiation small • Heaviside – Kennelly – ionosphere optically thick • No attempts for 30 years…

• 1930’s – transatlantic radio phone calls • Interference: 15-30m wavelengths • Bell Labs – Karl Jansky, engineer Karl Jansky

Karl Jansky & Grote Reber • Detected radio signals 1932 – Nearby thunderstorms – Distant thunderstorms – Faint steady hiss ??? • Sidereal, not solar  plane of our Galaxy • 1933 May 5 – NY Times announcement • Jansky wanted to do more – Bell labs didn’t… Grote Reber

WWII • Large resources put into radio, radar technology worldwide • During war: J.S. Hey (UK) finally discovered radio emission from the Sun, also Australian/NZ group (early morning jamming..) • After war: UK, Australia, Netherlands moved expertise and resources in “radio astronomy” • US – Caltech/Owens Valley in 1950s • National Radio Astronomy Observatory - 1956 Jodrell Telescope NRAO 300’ Parkes Telescope Effelsberg Radio Telescope Arecibo Observatory Green Bank Telescope Shanghai Tian Ma 65m Angular Resolution

Resolving power (how small of a thing you can “see”) depends on the size of the telescope and the wavelength of the light For radio waves, l this is large… size So this must also be large

“Size” = diameter of telescope for single dish; maximum distance between telescopes for arrays Radio Telescopes: Resolution

Size

Size

Single Dish Arrays Interferometer

Correlator

……Reconfigurable Early interferometers - Cambridge, UK

Cambridge 1mile & 4C Telescopes Westerbork Synthesis Radio Telescope Very Large Array

Australia Telescope Compact Array Allen Telescope Array Very Long Baseline Array Space VLBI

RadioAstron Atmosphere Low Frequency? LOFAR

Long Wavelength Array

Murchison Widefield Array

PAPER HERA High Frequency? South Pole Telescope Submillimeter Array Atacama Large Millimeter/submm Array - ALMA

Space? Radio Telescopes Around the World

WMAP (23-94 GHz) Planck (100-857 GHz) Herschel (>480 GHz) Wilkinson Microwave Anisotropy Probe (WMAP)

WK--bandband 2394 GHzGHz

Background=3 K blackbody radiation map.gsfc.nasa.gov Wikipedia: # Radio Telescopes >> 100 Square Kilometer Array SKA Components

• SKA-low – ~80-300 MHz, primarily Epoch of Reionization • SKA-mid – ~300 MHz-few GHz, primarily galaxy evolution (HI telescope) and Dark Energy; also gravity – Note: 1 km2 is nearly 6000 15m dishes!! • SKA-high – Few GHz to 25-50 GHz, primarily cradle of life (star and planet formation, galaxy formation)

• Phase 1 (first 10%) followed by Phase 2. Cosmic Dawn (First Testing General Relativity Stars and Galaxies) (Strong Regime, Gravitational Waves)

Galaxy Evolution (Normal Galaxies z~2-3) Cradle of Life (Planets, Molecules, SETI)

Cosmology (Dark Matter, Large Scale Structure) Cosmic Magnetism (Origin, Evolution)

Exploration of the Unknown Summary of the SKA Baseline Design

250,000 element 2020 96 survey enabled dishes

: Low Frequency Aperture Array

I

se ha

P 254 dishes

2024 >250,000 element Mid Frequency Aperture

: Low Frequency Aperture Array Array

II

se ha

P 2500 dishes

Cosmic Dawn & Reionization Cosmology & Pulsars Cosmic Magnetism Cradle of Life

Galaxy Evolution

ce

ien Sc

50 MHz 100 MHz 1 GHz 10 GHz SKA1-LOW:Australia ~130,000 antennas then 500,000 in Phase 2

Footer text SKA1-MID: Africa 200 15-m dishes across 150 km

~2,000 dishes in Phase 2, across southern Africa

Footer text Sensitivity Comparison Image Quality Comparison

“Structural” dynamic range of ~1000:1 rather than ~3:1 per VLA track (eg. SKA1-Mid vs. VLA A-config.) Image Quality Comparison

Single SKA1-Low track compared to LOFAR-INTL Central SKA2 South Africa Core Site: Potential Dish Array Transition from SKA1 (red) to SKA2 (blk)

Footer text SKA Organisation: 10 countries

Observers: • France • Germany • Japan Australia (DoI&S) • Malta Canada (NRC-HIA) • Portugal China (MOST) • Spain India (DAE) • Korea Italy (INAF) • USA Netherlands (NWO) New Zealand (MED) Contacts: South Africa (DST) • Brazil Sweden (Chalmers) • Ireland UK (STFC) • Russia • Switzerlan SKA HQ: Jodrell Bank, UKSKA HQ – Jodrell Bank, UK Australian SKA Prototype (ASKAP) MeerKAT

Precursor progress: MeerKAT • Effective area 10x JVLA, ALMA, located in US Southwest • Frequency range: 1 – 50, 70 – 115 GHz • ~18m antennas w. 50% to few km + 40% to 50km + 10% to 3000km? • Design goal: minimize mass production and operations costs Thermal Imaging on Milliarcsecond Scales

HL Tau – ALMA B6 Planet Formation on Milliarcsecond scales

Kraus et al. 2014 ngVLA: Terrestrial zone ALMA 250GHz Brogan ea. planet formation imager • Protoplantary disks: Inner ~ 20AU disk 100AU optically thick in mm/submm 0.7” at • Grain growth and stratification: from dust 140pc to pebbles to planets • Simulation  Jupiter at 13AU, Saturn at 6AU  Image both gaps + annual motions  Circumplanetary disks: planet accretion! ngVLA 100hr 25GHz 0.1” = 10mas 13AU

model model rms = 90nJy/bm = 1K ngVLA ngVLA

CHIME

Five hundred meter Aperture Spherical Telescope FAST

Technology Challenges • Antennas – cheap, mass production, low maintenance, accurate • Receivers – mass production, Phased Array Feeds, wide bandwidths • Cryogenics – large operations costs • Data transport – costs for high bandwidth backhaul • Correlators – scale, power • Data Management – PB, EB of data to be stored, processed – sometimes in real time… • Software/Processing • Access to next generation of scientists/engineers – you!! SKA Mid MeerKAT 15-m dish 13.5-m dish 32 tons 47 tons Phased Array Feeds

Data Management Global Software Infrastructure Summary • Many large radio interferometers operating/planned. • All facing growing challenges of data scale and complexity. • SKA and ngVLA – major challenges.

• Scientifically exciting future for radio interferometry ahead! Need a few (thousand) good people. 88 www.nrao.edu science.nrao.edu

The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.