Probing the primordial Universe with 21-cm line from cosmic dawn/epoch of reionization

Understand

In the most distant reaches of the Universe, the 21-cm hyperfine transition in neutral hydrogen provides one of the only available tracers of large-scale structure.

• A number of instruments have been working and planned to measure the 21-cm line signals, and in particular, Experiment to Detect the Global EoR Signature (EDGES) recently has reported the first detection of an absorption signal, which corresponds to the 21-cm line global signal at the epoch of reionization (EoR).
• The future large radio telescope, Square Kilometre Array (SKA) will be able to deliver the high-precision measurement of 21-cm line emission/absorption signals.
• In this paper, we review the current status for the 21-cm line global and fluctuation signals from EoR to the dark ages, and then summarize the recent studies of how we probe the primordial Universe particularly motivated by the recent EDGES result and future observations by SKA.