Browsing by Author "Matshawule, Siyambonga Donald"

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    HI intensity mapping: Impact of primary beam effects
    (University of the Western Cape, 2023) Matshawule, Siyambonga Donald; Santos, Mario G.
    Neutral hydrogen (HI) intensity mapping surveys with upcoming and future radio telescopes such as the MeerKAT, a precursor to the Square Kilometre Array Observatory (SKAO) MID telescope, have great potential for constraining cosmology, particularly in the post-reionization Universe provided that e ective cleaning methods are available to separate the strong foregrounds from the cosmological signal. The application of cleaning methods is usually conducted under the assumption of simplistic primary beam models. In this thesis, I simulate a single-dish wide-area survey with MeerKAT characteristics, and test foreground subtraction with a realistic model for the primary beam that contains a non-trivial frequency dependence. I also probe the impact of strong point sources on the cleaning. To conduct this evaluation, point source maps from a much more realistic full-sky point source catalogue are included as part of the foregrounds present in the sky model.
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    Probing the large-scale structure of the universe with correlation functions
    (University of the Western Cape, 2014) Matshawule, Siyambonga Donald; Maartens, Roy; Johnston, R. W
    In this project we explore a new statistical package called KSTAT that computes the 2PCF and higher order correlation functions, such as the 3PCF, on BOSS, making use of high performance computing facilities to improve optimization. The higher order statistics such as the 3PCF can be used to probe primordial non-Gaussianity. We present the first and most precise measurements of the reduced 3PCF (Q) measured using KSTAT on the DR10 data release at higher redshift, DR10 CMASS p z 0:5q and LOWZ p z 0:3q. Our reduced 3PCF results at low redshift z 0:3 are consistent with those of McBride et al. (2011a) at z 0:104 in the SDSS LRG sample. In this initial analysis, we have found no evidence of evolution of the 3PCF on small and large scales, however we do observe the characteristic U shape of the reduced 3PCF as one increases scale