| Description |
In this talk, I want to highlight two interesting probes of cosmic reionization — the recent 21cm power spectrum limits from the HERA telescope, and future high-redshift Fast Radio Burst observations. 21cm cosmology provides a unique window into the early universe, allowing us to observe neutral Hydrogen gas via its 21cm spin-flip transition, in principle allowing us to probe redshifts z=5 to 100. Using the recent HERA observations which provide the strongest limits on the 21cm power spectrum at z=8, we constrain models of reionization as well as properties of the IGM in the early universe. Fast Radio Bursts are recently discovered, very bright, radio transient signals observed from outside our galaxy. These bursts are dispersed due to the free electrons present in the IGM, and thus we can use them to probe the free electron content of the universe. Future observations (e.g. SKA) are expected to measure thousands of FRBs from high redshifts, and, thus, allow us to directly probe the reionization history of the IGM. We show how this, still very uncertain, history can be probed model-independently, without assuming a particular shape.
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