Some definitions:
SKA1 Low frequency range : 70 - 450 MHz
SKA1 Mid frequency range capability : 0.3 - 10 GHz (initial implementation 0.45 - 3 GHz)
It is proposed that Australia and New Zealand site the low frequency antennas.
The
SKA Working Group in 2007 identified two "major science goals which drive the technical specifications of SKA1" -
Quote:
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Originally Posted by SKA Memo 125
(i) Understanding the history and role of neutral Hydrogen in the Universe from the dark ages to the present-day, and
(ii) Detecting and timing binary pulsars and spin-stable millisecond pulsars in order to test theories of gravity
(including General Relativity and quantum gravity), to discover gravitational waves from cosmological sources,
and to determine the equation of state of nuclear matter.
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Neutral hydrogen (HI) is detected at what is known as the
hydrogen line which is at 1.42GHz (21cm).
However, it becomes red-shifted to lower frequencies for distant galaxies.
According to the abstract of
this 2009 Nature paper by Chang et. al -
Quote:
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Originally Posted by Chang et. al
Observations of 21-cm radio emission by neutral hydrogen at redshifts z ≈ 0.5 to ~2.5 are expected to provide a sensitive probe of cosmic dark energy.
This is particularly true around the onset of acceleration at z ≈ 1, where traditional optical cosmology becomes very difficult because of the infrared opacity of the atmosphere. Hitherto, 21-cm emission has been detected only to z = 0.24.
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This presentation by Martin Zwaan of ESO is entitled "All you would like to do with the SKA on neutral hydrogen" -
http://www.mpifr-bonn.mpg.de/div/mee..._VRS_Zwaan.pdf
It has slides which propose HI surveys at mid-frequency ranges at z<2 and also
HI surveys requiring a year of integration at z=3 (deep) using low frequencies (350MHz).
So the Australian and New Zealand low-frequency SKA antennas will play a vitally
important role in discoveries at the very distant, highly re-shifted (high z) extents of the
universe.
Congratulations to all those who worked so hard on the Australian and New Zealand bid.
Their forward thinking is going to enable us to look back close to the beginning of time.