PhD Defense Public Talk

The Epoch of Reionization was powered by ionizing photons produced within the first generations of galaxies, yet a fundamental question remains: what determines whether these photons escape their host galaxies and reach the intergalactic medium? Answering this question requires understanding the entire lifecycle of ionizing radiation-- from its production by massive stars to its propagation through the interstellar medium and its eventual escape or destruction.

In this dissertation, I use nearby star-forming galaxies as laboratories for studying each stage of this lifecycle. By analyzing spectroscopic observations spanning the ultraviolet to the mid-IR to the radio, I investigate how stellar populations produce ionizing radiation, how feedback reshapes the surrounding gas, and how these processes create pathways for photons to escape. I present new constraints on the neutral gas structures that regulate photon transport, evidence for multiple evolutionary channels of Lyman continuum escape, and spatial maps for one of the hardest ionizing radiation fields observed within a nearby galaxy.

These results connect the birth, life, and death of ionizing photons within star-forming galaxies in the nearby universe, providing a lens for better understanding the distant systems that reionized the Universe.