RSAA Colloquia / Seminars / Feast-of-Facts: Thursday, 15 September 2016, 11:00-12:00; Duffield Lecture Theatre

Katey Alatalo

"Catching Quenching Galaxies: Following the Roads Less Traveled to Galaxy Transformation"

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. I will discuss two such pathways galaxies take to rapidly transform from vibrant, blue spirals into quiescent, red elliptical and lenticulars, in particular, through the lens of the molecular gas. This includes the ways in which (1) AGN feedback (one of the proposed transformation mechanisms) and (2) constant harassment within compact groups can impact an environment that is rich in molecular gas, rendering it unable to form stars. I discuss new observations that have shown this phenomenon (as well as potential recipes to identify more of these objects), as well as the implications that these mechanisms have for galaxy evolution.