Description
1- What will it take to establish an initial 21 cm detection of either the fluctuating or global signal and convince the community that the measurement is real? Which systematics are most worrisome? How about for other line-intensity mapping (LIM) signals?
2- For interpreting 21 cm/LIM/kSZ measurements, how should we best parameterize our ignorance of the ionizing sources and other relevant, yet uncertain, quantities? How do we incorporate observational constraints into our models and which current/future observations are most useful? Which aspects of 21 cm/LIM/kSZ modeling are least under control?
3- How to best extract the reionization-era kSZ signal and what will we learn from it? How do we separate it from the post-reionization kSZ and other foregrounds?
4- What are the most interesting plausible signatures of dark matter properties in future 21 cm measurements during reionization, cosmic dawn, and the dark ages?
