The Production and Transmission of Lyman-alpha Photons in High-redshift Galaxies and the Implications for the Escape of Ionizing Radiation

Prof. Naveen Reddy (UC Riverside)
Tuesday, February 22, 2022 - 11:00am

The epoch of reionization (EoR) was a landmark event, when radiation from the first stars and accreting black holes permeated the intergalactic medium (IGM) and ionized hydrogen.  A key focus of observational cosmology is to determine the sources that reionized the universe at z>6 and maintained the ionization of the IGM at lower redshifts.  In spite of significant efforts focused on the demographics of star-forming galaxies at the EoR, we are still far from understanding how reionization proceeded due to difficulties in quantifying the escape fraction of ionizing photons.  I will discuss recent work that uses the Lyman-alpha (Lya) emission from z~2-3 galaxies to uncover the role of stellar populations and gas covering fraction on the escape of Lya and Lyman continuum (LyC) ionizing photons.  I will present evidence that such escape is aided by a compact configuration of star formation coupled with a low gravitational potential.  I will also present new Keck/KCWI observations of confirmed LyC-leaking galaxies that reveal the diversity of pathways by which LyC radiation escapes galaxies.

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