SKA Weak Lensing II: Simulated Performance and Survey Design
  Considerations
  We construct a pipeline for simulating weak lensing cosmology surveys with
the Square Kilometre Array (SKA), taking as inputs telescope sensitivity
curves; correlated source flux, size and redshift distributions; a simple
ionospheric model; source redshift and ellipticity measurement errors. We then
use this simulation pipeline to optimise a 2-year weak lensing survey performed
with the first deployment of the SKA (SKA1). Our assessments are based on the
total signal-to-noise of the recovered shear power spectra, a metric that we
find to correlate very well with a standard dark energy figure of merit. We
first consider the choice of frequency band, trading off increases in number
counts at lower frequencies against poorer resolution; our analysis strongly
prefers the higher frequency Band 2 (950-1760 MHz) channel of the SKA-MID
telescope to the lower frequency Band 1 (350-1050 MHz). Best results would be
obtained by allowing the centre of Band 2 to shift towards lower frequency,
around 1.1 GHz. We then move on to consider survey size, finding that an area
of 5,000 square degrees is optimal for most SKA1 instrumental configurations.
Finally, we forecast the performance of a weak lensing survey with the second
deployment of the SKA. The increased survey size (3$\pi$\,steradian) and
sensitivity improves both the signal-to-noise and the dark energy metrics by
two orders of magnitude.
