SKA 2004

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SKA 2004

• Exploration of the Unknown
• R. D. Ekers
• CSIRO, Australia Telescope National Facility
• Penticton
• July 20 2004

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Be prepared for the unexpected

• Most major discoveries in science are not
  predicted
• Serendipity
• Astronomy is different from other sciences
• We can only explore the distant universe by
  observing the radiation which reaches us
• We can not normally do experimental physics
• A time of rapid change
• The excitement of the SKA will not be in the old
  questions which will be answered, but the new
  questions which will be raised by the new
  observations.
• This puts a premium on SKA for the exploration of
  the unknown

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Technology leads scientific discoveries

• De Solla Price most scientific advances follow
  laboratory experiments
• Martin Harwit most important discoveries result
  from technical innovation
• Discoveries peak soon after new technology
  appears
• usually within 5 years of the technical
  capability
• Many examples from radio astronomy
• Quasars, Pulsars, CMB.
• Successful telescopes are built by visionaries
  but often for the wrong reason

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Predicting v Explaining

• When there are few degrees of freedom there may
  be only a few solutions given the rules
• Predictions are possible
• Even small observational constraints are
  important
• Eg CMB
• When there are many degrees of freedom there are
  many solutions
• Predictions are now become unlikely and are less
  valuable
• Observations guide interpretation
• Common user facilities are mostly used as an
  analytic tool
• How to separate unexpected discoveries from errors

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Galileo Galilei - 1609

• Galileo builds his first telescope and he sees
  the moons of Jupiter.

Four planets, never seen since the beginning of
the World right up to our day
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Karl Jansky Bell Telephone Laboratory 1933
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Beginning of Radio Astronomy

• Jansky
• signal arrives 4 min earlier each day
• reaction from Bell Labs so faint not even
  interesting as a source of radio interference!
• not accepted by the astronomical community at
  the time
• no theoretical framework
• Pasteur
• In the field of observation, chance favours the
  prepared mind

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VLA Science

• Funding Proposal (1967)
• Key scientific drivers (8 pages)
• radio galaxies, quasars, cosmology
• Other science which may benefit
• planets, galactic studies, 21cm Hydrogen line
• Science being done (1980-1991)

• stars (16)
• galaxies (14)
• radio galaxies (13)
• Quasars (9)
• star formation (9)
• solar system (6)
• AGN (5)
• Supernovae (4)

• Intersellar medium (4)
• cosmology (4)
• molecules (3)
• galactic centre (3)
• VLBI (3)
• pulsars (2)
• Xray etc (1)
• Astrometry (1)

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Large radio telescopes make discoveries!

• Quasars and radio galaxies

• Serendipity

- 21cm HI line

• Cosmological evolution of radio sources

• Cosmic Microwave Background

• Jets and super-luminal motions

• Dark matter in spiral galaxies

• Masers and megamasers

- Mass of the blackhole in AGN NGC4258

• Pulsars

- Gravitational radiation (pulsar timing)
- First extra-solar planetary system
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Large radio telescopes make discoveries!

• Quasars and radio galaxies

• Technology

• 21cm HI line

• Cosmological evolution of radio sources

• Cosmic Microwave Background

• Jets and super-luminal motions

Dark matter in spiral galaxies

• Masers and megamasers

- Mass of the blackhole in AGN NGC4258

• Pulsars

- Gravitational radiation (pulsar timing)
- First extra-solar planetary system
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Discovery Space what is left, where are the
gains ?

• New wavelengths - just about finished
• Angular resolution
• radio already in space,
• plenty of scope at other wavelengths
• Time resolution
• Polarization
• Volume of space sampled ? biggest gains now here
• Increases sample of rare objects
• Sensitivity ELTs, EVLA, SKA
• Field of view SKA
• Statistics as well as signals

Sensitivity Dynamic range
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SKAs 1o field-of-view

• surveys and transient events in 106 galaxies !

SKA 20 cm
ALMA
15 Mpc at z 2
Now 10x10o !
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New observing paradigms

• Multiple simultaneous FoV
• Changes observing style
• Dedicated beams
• High risk experiments
• Beams for other communities (educational)
• Transients before they happen
• Baseband buffer

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SKA Poster
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Multi beams
Element antenna pattern
Station antenna patterns
Synthesized beams
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• Observing teams with their own beams
• like particle accelerator, but can have all beams
  simultaneously
• Baseband buffer
• Observe before trigger !

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NFRA 1998
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What does this mean for the SKA?

• Maximum flexibility in the design
• Exploit areas of fastest changing in technology
• Signal processing hardware late
• Software development early
• Maintain the technical expertise in community
• Not the VLA example
• Clear user interface
• Open system design?
• Software, hardware
• Multiple reuse of expensive components
• Area, wavelength, bandwidth
• Pathfinders
• Technical and scientific to adapt to change