Weak Lensing Simulations for the SKA
  Weak gravitational lensing measurements are traditionally made at optical
wavelengths where many highly resolved galaxy images are readily available.
However, the Square Kilometre Array (SKA) holds great promise for this type of
measurement at radio wavelengths owing to its greatly increased sensitivity and
resolution over typical radio surveys. The key to successful weak lensing
experiments is in measuring the shapes of detected sources to high accuracy. In
this document we describe a simulation pipeline designed to simulate radio
images of the quality required for weak lensing, and will be typical of SKA
observations. We provide as input, images with realistic galaxy shapes which
are then simulated to produce images as they would have been observed with a
given radio interferometer. We exploit this pipeline to investigate various
stages of a weak lensing experiment in order to better understand the effects
that may impact shape measurement. We first show how the proposed SKA1-Mid
array configurations perform when we compare the (known) input and output
ellipticities. We then investigate how making small changes to these array
configurations impact on this input-outut ellipticity comparison. We also
demonstrate how alternative configurations for SKA1-Mid that are smaller in
extent, and with a faster survey speeds produce similar performance to those
originally proposed. We then show how a notional SKA configuration performs in
the same shape measurement challenge. Finally, we describe ongoing efforts to
utilise our simulation pipeline to address questions relating to how applicable
current (mostly originating from optical data) shape measurement techniques are
to future radio surveys. As an alternative to such image plane techniques, we
lastly discuss a shape measurement technique based on the shapelets formalism
that reconstructs the source shapes directly from the visibility data.
