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Epoch of Reionisation Program Student Projects

3rd year/Honours

Title: Applications of wavelets for exploring the Epoch of Reionisation

Supervisors: Dr Cathryn Trott, Dr Steven Murray

The Epoch of Reionisation (EoR) marks a crucial period in the evolution of the early Universe, during which the first collapsed structures (stars and galaxies) illuminated the cosmos with ionizing radiation and destroyed the neutral hydrogen gas permeating the intergalactic medium. We can probe the evolution of structure in this period by studying the spatial and temperature distribution of neutral hydrogen, through the redshifted emission line from its nucleus. This measurement can be achieved with low-frequency radio telescopes, such as the Murchison Widefield Array (MWA) and future Square Kilometre Array (SKA), in the Western Australian desert. We use statistical techniques, such as a spatial power spectrum, to combine data from the weak signal in the hope of a detection. These techniques rely on a Fourier Transform of the data, but are limited by their ability to balance increased sensitivity (more data) with biased results (due to evolution of the signal over redshift). We recently proposed using a wavelet basis to address this deficiency. This project will explore other wavelet basis functions, to see their effect on a signal and foreground galaxy model, already developed. This project would suit a student with an interest in and knowledge of statistical techniques, such as the Fourier Transform and wavelets, and some knowledge of basic computing.

 

3rd year/Honours

Title: Defining the observing strategy for the SKA Epoch of Reionisation Experiment

Supervisors: Dr Cathryn Trott, Dr Natasha Hurley-Walker

The statistical Epoch of Reionisation program for the Square Kilometre Array (SKA) comprises a three-tiered experiment: shallow and wide, medium, deep and narrow. The deepest observations are required for probing the power spectrum of brightness temperature fluctuations at low frequencies, where the experiment is thermal-noise limited. The shallow observations serve the higher frequencies, where sample variance is important. The choice of observing fields for these experiments is crucial; balancing sky coldness, availability of sufficient data calibrators, and frequency-dependent field-of-view. Using the GLEAM catalogue of the radio sky at 80-230 MHz, this project will overlay the SKA frequency-dependent sky response (primary beam) over the sky, and extract useful field-dependent statistics to help define the observing strategy. This work will feed directly into the Observational Strategies working group of the EoR/Cosmic Dawn Key Science Project.