Constraining the Reionization Process via 21-cm Power Spectra

• Main Authors: Fang-Chun Liu, 劉芳君
• Other Authors: Tzu-Ching Chang
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/46893488581119280773

碩士 === 國立臺灣大學 === 天文物理研究所 === 102 === Up to date there has been little observational constraints on the cosmic reionization process, the phase transition of the universe caused by the for- mation of the first luminous objects. Current theoretical modelling of reion- ization is subject to large uncertainties due to the complex astrophysical pro- cesses. In this thesis, we use a publicly available semi-numerical package, 21cmFAST (Mesinger et al. 2011), to simulate a large comoving cosmic vol- ume and explore key astrophysical parameters that impact the neutral hydro- gen 21-cm power spectra during reionization. We construct the Fisher infor- mation Matrix to quantify the impact of these astrophysical parameters, and make forecasts on how well we can constrain the reionization process given an experimental design, such as the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometer Array (SKA1-low). We quantify the im- pact of model parameters as a function of redshifts. We find the star formation efficiency affects more on power spectra at high redshift 21 &;#8818; z &;#8818; 26 and less at late stage of reionization. The number of UV photon per baryon influences more before the reionization starts with a peak at redshift z &;#8764; 24, and drops rapidly after Lyα coupling saturates. The X-ray heating mechanism peaks at redshift z &;#8764; 21, and provides the most heating on the low density Intergalac- tic Medium (IGM) due to the long mean free path. We also find the fraction of the UV photons escape from their host galaxies into the IGM impact the 21-cm power spectra at the final stage of the reionization process.