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The Phase II of Murchison Widefield Array Experiment: Constraining the Epoch of Reionization

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Abstract:
The detailed physics of the first luminous objects and the subsequent Epoch of Reionization (EoR) remains largely unknown. The most promising approach for placing observational constraints on the EoR is to detect the 21 cm emission from hyper-fine spin flip transition in neutral hydrogen. By observing the redshifted 21 cm emission from the neutral intergalactic medium (IGM) we are potentially able to make a 3D map of structure evolution. However, current experiments do not have the sensitivity to directly image the 21 cm signal. We instead use a statistical quantity, the 21 cm power spectrum, to quantify the 21 cm power at various spatial scales. The Murchison Widefield Array (MWA) located in Western Australia is one of the first generation telescopes targeting the EoR. The recent Phase II upgrade to the MWA has improved the EoR power spectrum sensitivity, as well as has provided new opportunities for redundant calibration. In this work, I developed new analysis techniques to remedy the contamination from foregrounds, Radio Frequency Interference (RFI), and instrument-specific artifacts. By applying this improved instrument calibration technique, as well as better data quality evaluation metrics, the errors in traditional analysis have been mitigated, and the constraints on power spectrum has been improved. By analyzing 40 hours of MWA Phase II EoR observation, we show the measured power spectrum at $0.18hMpc^{-1}<k<1.6hMpc^{-1}$ with a lowest observed upper limit of $\Delta^2=2.39\times 10^3 mK^2$ at $k=0.59 hMpc^{-1}$ and $z=6.5$.
Notes:
Thesis (Ph. D.)--Brown University, 2019

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Citation

Li, Wenyang, "The Phase II of Murchison Widefield Array Experiment: Constraining the Epoch of Reionization" (2019). Physics Theses and Dissertations. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:1129504/

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