Speaker: Molly Wolfson (UC Santa Barbara)
Constraining Reionization with the z > 5 Lyman-α forest
One of the most important open problems in cosmology is understanding the reionization of the intergalactic medium (IGM) by the first luminous sources. This happened during a time period now known as Reionization and is generally believed to be complete at z > 5. During Reionization ionization fronts propagate through the IGM, heating the reionized gas. This heat injection can be observed over a redshift interval of ∆z ∼ 1 due to the long cooling times in the low-density IGM. Simultaneously, the mean free path of ionizing photons (λmfp) describing the ultraviolet background (UVB) rapidly evolves as bubbles of reionized gas, where the UVB is stronger, merge. Thus, constraining the thermal state of the IGM and the evolution of λmfp can, in turn, be used to constrain Reionization. Transmission in the Lyman-a (Lya) forest, the ubiquitous Lya absorption lines produced by residual neutral hydrogen in the IGM along quasar sightlines, is sensitive to both of these phenomena. I will discuss my work showing that the Lya forest flux auto-correlation function can be used to constrain the thermal state of the IGM as well as λmfp. In addition, I will introduce my measurement of the flux auto-correlation functions at z > 5 from the XQR-30 extended data set, the first measurements of this statistic at these redshifts.
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