Galaxy Build-up During the Cosmic Reionization Epoch

Cosmic Reionization represents the last major phase transition of the Universe, from a neutral to an ionized inter-galactic medium. Over the last two decades, we have made great progress in mapping out the history and the timing of this reionization process, finding it to be largely complete by z~6, i.e. 1 Gyr after the Big Bang. At the same time, astronomers have identified large samples of galaxies at z>6, which allow us to directly trace galaxy build-up in the heart of the reionization epoch. However, whether these sources were sufficient to drive reionization is still an open question. Furthermore, the spectroscopic exploration of these galaxies is still very limited. Only a handful of the brightest sources are currently detected with spectroscopy, severely limiting our insights into their physical properties and chemical build-up. In this talk, I will review recent observational progress in the study of the first generations of galaxies and I will highlight the revolutionary possibilities that are ahead of us with the launch of future facilities such as the JWST or Euclid.