Richard Ellis plenary: Let There Be Light: The Observational Quest for the First Galaxies

The first billion years after the Big Bang can be regarded as 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 for the first time. Sometime during this era, hydrogen in the intergalactic medium also transitioned from a neutral gas to one that was fully ionized. How and when did this `cosmic reionization' occur and were early star-forming galaxies the primary agents?

Deep exposures with the Hubble Space Telescope have provided the primary evidence that star-forming galaxies were present during the relevant period. Detailed spectroscopy of these galaxies is now required to address these important questions. In this plenary session, Richard Ellis of the European Southern Observatory reviews the rapid progress being made in this area with current facilities, and the prospects with upcoming ones, including the James Webb Space Telescope and extremely large ground-based telescopes now under construction.

Richard Ellis studied at London and Oxford Universities and served as a professor and department head at Durham and Cambridge Universities. He moved to Caltech in 1999 to assist in developing the ThirtyMeter Telescope and was Director, Caltech Optical Observatories from 2000-2006. He returned to University College London in 2015 and is currently on leave as Senior Scientist at the European Southern Observatory.