Epoch of Reionization

Epoch of Reionization Working Group Introduction

When did the first generations of galaxies form? What were their properties? How did they interact with each other? What is the structure of the intergalactic medium during the first billion years? What is the thermal and ionization history of the baryons?

The footprint of these processes is imprinted in the Hydrogen gas the major constituent of the intergalactic medium) and can be probed by observations of its hyperfine spectral line transition (occurring at the rest frequency of 21-cm). We plan to use the SKA to carry out the deepest observations of the diffuse neutral Hydrogen gas to trace the evolution of cosmic structure in the 6 < z < 30 range, unveiling the epoch when the very first luminous structure were born and how their growth ionized the intergalactic medium.