Cosmos Seminar
Nov
13
2025
Nov
13
2025
Description
Galaxies, Bubbles, and Lyman-Alpha: Mapping the Patchy Universe at Cosmic Dawn
The Epoch of Reionization (EoR) marks the Universe’s pivotal phase transition: when the first luminous sources transformed a fog of neutral hydrogen into a transparent, ionized intergalactic medium (IGM). Lyman-alpha (Lyα) emission, the most prominent spectral feature in star-forming galaxies, provides a powerful probe of this process: because it is resonantly scattered by neutral hydrogen, its presence, absence, and spectral shape encode where the IGM is ionized and how ionized bubbles grow. A suite of Lyα observables (e.g., equivalent width, luminosity function, spectral line profile, and damping-wing attenuation) reconstructs both the timeline and topology of reionization and links those maps back to the physics of galaxies and stars. I will discuss what recent discoveries imply about the ionizing sources and geometry of reionization, addressing key physical and observational challenges such as cosmic variance, sight-line dependence, and evolving ISM/CGM conditions. Finally, I will outline future directions aimed at advancing Lyα observations toward a more physically grounded and statistically robust view of the Universe’s last major transformation.
Other Events in This Series
Jan
23
2025
Cosmos Seminar: Seeking to Uncover The Obliquities of Small Planets
Jack Lubin is a postdoctoral researcher in Astrophysics at the University of California, Los Angeles
3:30 pm – 4:30 pm • In Person
Speaker(s): Jack Lubin - UCLA
Mar
13
2025
Cosmos Seminar
Cosmos Seminar
3:30 pm – 4:30 pm • In Person
Speaker(s): William Roper - University of Sussex and Stephen Wilkins - University of Sussex