Cosmic reionization is the last cosmological phase transition. There is strong observational evidence that it ended nearly one billion years after the Big Bang. The first generations of galaxies primarily powered this grand event in the cosmic timeline. Because structure forms hierarchically, these first galaxies are the building blocks of all galaxies we see today, and their properties are passed along as galaxies assemble. Thus, further constraints from the epoch of reionization will play a key role in solidifying theories of galaxy formation and cosmology.
However there still are unanswered questions in its exact timing, its progression, its nature, and the role of the first galaxies played during the epoch of reionization. These questions will be elucidated with the upcoming James Webb Space Telescope, ground-based 30-m class telescopes, and more accurate CMB and 21-cm experiments, all set to be commissioned within the next decade. Observing both the reionizing universe and the galaxies responsible for this transition is paramount in augmenting our knowledge of this formative period in the universe.
Acknowledgments
Many throughout my academic career have contributed to my understanding of the first stars, first galaxies, radiation transport, and reionization, but I want to give special thanks to Tom Abel, Marcelo Alvarez, Renyue Cen, Andrea Ferrara, Andrei Mesinger, Michael Norman, Brian O’Shea, John Regan, Britton Smith, and Matthew Turk. My research is currently supported by National Science Foundation (NSF) grants AST-1614333 and OAC-1835213, NASA grant NNX17AG23G, and Hubble theory grant HST-AR-14326.
Notes on contributor
John Wise is the Dunn Family Associate Professor in the School of Physics and Center for Relativistic Astrophysics at the Georgia Institute of Technology. He uses numerical simulations to study the formation and evolution of galaxies and their black holes. He is one of the lead developers of the community-driven, open-source astrophysics code Enzo (enzo-project.org). He received his B.S. in Physics from the Georgia Tech in 2001. He then studied at Stanford University, where he received his Ph.D. in Physics in 2007. He went on to work at NASA’s Goddard Space Flight Center as a NASA Postdoctoral Fellow. Then in 2009, he was awarded the Hubble Fellowship which he took to Princeton University before arriving at Georgia Tech in 2011, coming back home after ten years roaming the nation.