Abstract:
Stacking is a statistical approach to measure the average properties for known objects that are too faint to be detected individually at the target wavelength. This
approach has been extensively used for studies of high redshift, and/or intrinsically
faint galaxies with a wide range of telescopes, including radio inteferometers. The
technique is typically applied using images rather than the direct measurement of
an interferometer, namely Fourier components of the sky brightness distribution.
However, interferometry is not a direct imaging method, and this imposes several
challenges to stacking, limiting scientific inference. This thesis tests where visibility
stacking might be more effective than the traditional image-plane stacking approach
using simulated data, as well as real observations from the MeerKAT telescope. To
do so, we perform a suite of visibility stacking experiments on realistic synthetic data
generated from the TRECS Square Kilometre Array simulations. Parameters that are
varied include the CLEAN depth, stacking depth and the maximum source distance
from the phase centre. We further investigate the applications of visibility stacking
on real MeerKAT data. The stacking techniques are applied on HI-selected galaxies
within the Abell 3408 galaxy cluster. Our simulated and real data results suggest
that visibility stacking produces favourable results compared to image-stacking for
shallow observations, but caution must be applied to sub-µJy stacked sensitivity experiments.
