Today's Colloquium: Catching Quenching Galaxies: Following the Roads Less Traveled to Galaxy Transformation

© Katherine Alatalo (The Carnegie Observatories)

Modern day galaxies are found to be in a bimodal distribution, both in terms of their morphologies, and in terms of their colors, and these properties are inter-related. In color space, there is a genuine dearth of intermediate colored galaxies, which has been taken to mean that the transition a galaxy undergoes to transform must be rapid. Given that this transformation is largely one-way (at z=0), identifying all initial conditions that catalyze it becomes essential.

I will discuss a new way we have identified to find such transitioning galaxies (through the Shocked POststarburst Galaxy Survey), which is able to pinpoint transitioning galaxies at an earlier stage of transition than other traditional searches. I will also discuss the case study of AGN-driven molecular outflow NGC1266, and new findings about the feedback between the interstellar medium in transforming galaxies and their transformations, in particular, the presence of star formation suppression being discovered taking place in the molecular gas reservoirs of these sources.

Between identifying new transforming galaxies, and providing new insights into the internal processes within transforming galaxies, a new window has been opened into this nearly one-way process.