Collaborative Research: Modeling the Reionization of the Intergalactic Medium

University Of Washington, Seattle WA

Investigators

Abstract

Reionization is the epoch during which intergalactic hydrogen was ionized, the period when the first galaxies formed and when the intergalactic gas was significantly heated, to tens of thousands of degrees Kelvin, but despite its importance, little is known definitively about this phase transition. This project aims to resolve the impact of self-shielding systems, perhaps the largest still unquantified uncertainty in current models of reionization, through a rigorous program of numerical simulations. Prior radiative transfer simulations did not have the resolution to capture self-shielding systems, and thus misestimated the total number of recombinations, biasing their predictions for the duration of reionization. Starting with a physically motivated model that includes self-shielding regions and explores parameter space with relatively inexpensive simulations, the work will use those results to carry out the first simulations with sufficient resolution to resolve self-shielding systems. Those simulations will verify the results from the initial work, and will be a resource for statistical studies on the structure of reionization. This study will understand how the violent relaxation of gas from photoheating during reionization influences dense gas and, hence, self-shielding systems, and will generally aid the interpretation of all observations of the reionization era. The data set of state-of-the-art reionization simulations will be made public and can be analyzed by the scientific community. Past work by this team has been used in many unaffiliated studies and the new results should also be of great utility. Similarly, the publicly available archive of visualizations will both educate the public and help to develop scientists? intuition. Supported undergraduate researchers will be drawn preferentially from under-represented groups, and the researchers intend public lectures at schools and other venues.