Let There Be Light: The Observational Quest for the First Galaxies
Prof. Richard Ellis
ESO and UCL
June 12, 2017 – 3:00 pm – Woolnough Lecture Theatre – Geology Department (UWA campus).
The first billion years after the Big Bang represent the final observational frontier in assembling a coherent picture of cosmic history. During this period early stars and galaxies formed and the Universe became bathed in ultraviolet light. Hydrogen in the intergalactic medium also transitioned from a neutral gas to one that was fully ionized. How and when did this `cosmic reionisation’ occur and were star-forming galaxies the primary agents? Recent measurements by the Planck satellite suggest reionisation occurred later than originally envisaged and this raises the exciting prospect that we may be able to directly observe the first galaxies. Deep exposures with Hubble provides evidence that star-forming galaxies were present during the relevant period. Spectroscopy is now required to address these important questions. I will review the rapid progress being made with current facilities, and the prospects with the James Webb Space Telescope and the ELT.