The reionization of the intergalactic medium (IGM) at z > 6 is one of the major transformations in the universe’s history, but we do not yet know which galaxies were responsible for this event. Although JWST is revealing the properties of galaxies from this epoch, it cannot directly detect their escaping ionizing radiation. Because these Lyman continuum (LyC) photons are absorbed by the IGM en route to Earth, we must instead investigate LyCescape using lower-redshift samples. I will share recent results from the Low-redshift Lyman Continuum Survey, the largest survey of LyC emission at low redshift, which is helping us understand how galaxy properties promote LyC escape. With HST UV observations of 66 galaxies, this survey has nearly tripled the number of low-redshift LyC detections, enabling us to systematically test proposed indirect diagnostics of LyC and establish the physical properties of LyC-emitting galaxies. These observations have given us new insights into feedback and interstellar gas in highly star-forming galaxies and are illuminating the possible characteristics of the galaxies that reionized the Universe. 

Speaker: Anne Jaskot (Williams College)

The 2025 Spring Colloquium talks are held on Wednesdays at 3:00 PM. This colloquium is hosted by STScI and will be held as an in-person and virtual event.

You may join in person at STScI’s John N. Bahcall Auditorium or virtually on STScI's Live Science Events Facebook page.

Please direct questions or comments to contact above. The 2025 Spring Colloquium Committee members are: Nestor Espinoza (STScI), Joel Green (STScI), Nick Indriolo (STScI), Elena Manjavacas (STScI), Namrata Roy (JHU), Kevin Schlaufman (JHU), Ethan Vishniac (JHU).