21cm Radio Cosmology
Supervised by Eloy de Lera Acedo and Dominic Anstey, and funded by the STFC, I am working on developing Bayesian data analysis techniques for the REACH radio telescope.
REACH
REACH (Radio Experiment for the Analysis of Cosmic Hydrogen) is a low-frequency radio experiment located in the South African Radio Astronomy Observatory (SARAO) in the Karoo desert. It is designed to measure the global 21-cm signal from neutral hydrogen in the early Universe, which can be used to constrain cosmological parameters and test models of structure formation.
Due to the large dynamic ranges involved in separating the cosmological 21-cm signal from the galactic synchrotron emission and instrumental systematics, it is imperative that we have precise analysis techniques which can constrain our modelling of the external effects which will confuse our signal detection.
Time-Varying Systematic Mitigation
Using Gaussian Processes we developed a method of mitigating the effects of unmodelled systematics on our ability to fit for the 21cm global signal (
Kirkham et al. 2023). Here we found that by using GPs to fit for time covariances in the model residuals increased our uncertainties in the parameter estimation, generally improving the error of our fits when compared with the standard REACH pipeline (
Anstey et al. 2021,
2023).
Calibration
I am continuing work on the calibration of the REACH receiver using Bayesian noise wave techniques (
Roque et al. 2021,
Kirkham et al. 2024). Through this work I have developed numerous calibration techniques (Kirkham et al. in prep, Bucher et al. in prep) which push forward our understanding of REACH calibration. I am also the builder and maintainer of the REACH calibration pipeline, which allows all members of the calibration to calibrate data with a simple intuitive interface.
Publications