Molly Wolfson & Jubee Sohn

Talk 1: Molly Wolfson, 3:00pm - 3:30pm
Constraining reionization with the Lyman-a forest flux auto-correlation function
Reionization is a major phase change in our universe’s history and understanding this transition remains a major open problem. One measurable signature of reionization is the mean free path of ionizing photons (λmfp) which rapidly evolves at the end of reionization as bubbles of reionized gas merge. Recently, λmfp has been measured to be small at z = 6 indicating a late end to reionization. Lyman-α (Lyα) forest transmission towards high-z quasars is sensitive to λmfp via the level of spatial fluctuations in the ultraviolet background (UVB). I will illustrate how the auto-correlation function of Lyα forest flux can therefore be used to measure λmfp. I will also present my measurements of the auto-correlation functions of the XQR-30 extended data set at 5.1 ≤ z ≤ 6.0, in search of further evidence for the rapid evolution of λmfp, and discuss the UVB fluctuation models needed to get maximal information from these measurements.

Talk 2: Jubee Sohn, 3:30pm - 4:00pm
Measuring velocity dispersion functions of cluster galaxies based on dense spectroscopy