Testing Gravity with MeerKAT and the SKA
Abstract
The new 64-dish radio telescope array MeerKAT will be absorbed into the international
Square Kilometre Array (SKA) in late 2020s. These two telescope arrays will
produce three-dimensional maps of the integrated intensity of the 21cm emission
from neutral hydrogen in galaxies, out to redshifts of 1:5 and 3 respectively. These
maps contain a signature of the growth of large-scale structure in the Universe.
This signature can be uncovered via redshift space distortions of the two-point
correlation function, or power spectrum, of the 21cm brightness temperature
uctuations.
The growth rate governs the amplitude of the anisotropic signal from
redshift-space distortions. It is a powerful probe of gravity and its measurement
has the potential to test whether general relativity holds. We use models of the
21cm intensity and its power spectrum, starting from a simple linear model of
redshift-space distortions and then extending to nonlinear models. With these
models, we make Fisher forecast predictions of the precision with which MeerKAT
and the SKA can measure the growth rate