| Abstract: |
Hydrogen reionisation is a crucial period during the Universe's history during which the first galaxies drive a global phase transition signalling the end of the Cosmic Dark Ages. Our observational view of reionisation has changed drastically since Planck measurements pushed the timing of the process to later times, and in reach of direct observation through quasar spectroscopy. Ironically, the increase in observational data has raised more questions than it has answered. The timing of the end of reionisation, as well as its morphology and the processes driving its end stages, are being hotly debated. I will review our current understanding of reionisation's end stages, and present preliminary results from the XQR-30 collaboration: a 248-hour Large Program which is increasing the number of high-quality quasar spectroscopy during reionisation four-fold. New developments are happening very quickly, and offering the first solid insights into the properties of early galaxies driving reionisation during the first billion years. |
