2022-11-04 11:00  P5A-1/Online

Catch in act: tracing the evolution of galaxies in transformation

Prof. Po-Feng Wu

A fundamental constraint on studying galaxies is that we are not able to monitor individual galaxies throughout their lifetime to track the evolution. The stars in galaxies provide fossil records on the build-up processes of galaxies. I will demonstrate that with current observing facilities, we are able to track the evolution of individual galaxies from their stellar populations. The archaeological method can date the ages of galaxies and pinpoint where they are in their evolutionary process. This ability is particularly helpful to answer one of the biggest unsolved questions in galaxy evolution: what happened in galaxies when they stopped forming new stars? With the galaxy formation histories extracted from their spectra, I identify galaxies that are right in the transitioning phase. Their physical properties inform us the mechanisms that drive galaxy evolution, which validates and challenges galaxy formation theories simultaneously.