Probing "Parent Universe" in Loop Quantum Cosmology with B-mode Polarization in Cosmic Microwave Background

• Main Authors: Wen-Hsuan Lucky Chang, 張文軒
• Other Authors: Jiun-Huei Proty Wu
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/924j69

博士 === 國立臺灣大學 === 物理學研究所 === 107 === We aim to use the observations of B-mode polarization in the cosmic microwave background (CMB) to probe the ``parent universe'' under the context of loop quantum cosmology (LQC). In particular, we investigate the possibility for the gravitational waves (GWs) such as those from the stellar binary systems in the parent universe to survive the big bounce and thus to be still observable today. Our study is based on the background dynamics with the zeroth-order holonomy correction using the Arnowitt-Deser-Misner (ADM) formalism. We propose a new framework in which transfer functions are invoked to bring the GWs in the parent universe through the big bounce, inflation, and big bang to reach today. This transparent and intuitive formalism allows us to accurately discuss the influence of the GWs from the parent universe on the B-mode polarization in the CMB today under backgrounds of different LQC parameters. These features can soon be tested by the forthcoming CMB observations and we note that the LQC backgrounds with symmetric bouncing scenarios are ruled out by the latest observational results from Planck and BICEP2/Keck experiments.