Dartmouth Events

Abstract: Early-type galaxies (elliptical and lenticular galaxies) are high-entropy stellar systems, all galaxies will eventually tend toward such states (perhaps sped up by interactions with other galaxies). Many early-type galaxies are also high-entropy gaseous systems, essentially with hot gas atmospheres maintained by energy input from their central super-massive black hole, not entirely differently than how central nuclear reactions support stars. However, some early-type galaxies still contain low-entropy, cold gas. In these cases, the galaxies are not quite in an ``end state”. I will discuss possible evolutionary pathways and physical processes that explain how some early-type galaxies still have cold gas reservoirs.