This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Dr. Bernardi will continue her investigations of the evolution of the optical depth in the Lyman-Alpha Forest using a much larger sample than previously available. Past work has shown that a sharp change in optical depth at a redshift of 3.2 is very likely due to He II reionization. The work to be carried out here will attempt to solidify this conclusion using a much larger dataset derived from the Sloan Digital Sky Survey Data Release 7. The data will also be used to study the patchiness of reionization, which will place constraints on models for the origin of the ionizing photons. Broader impacts of this effort include training of a graduate student.
