The authors of this paper pursued a mechanism which could possibly keep dead galaxies from forming new stars: mass ejected from AGB stars moving through the galaxy could heat the ambient gas.
Nature vs. nurture in the evolution of galaxies is not completely understood. Where a galaxy is found, its environment, can play an important role in determining the properties of that galaxy. This may not always be true, however.
Satellite galaxies orbiting a host galaxy seem to display highly anisotropic angular distributions.
How well do the current methods of measuring the star formation rate of galaxies match then known star formation rate in simulations?
As galaxies evolve they eventually stop forming stars. There are a host of (sometimes violent) processes that can end star formation in galaxies. The authors examine how galaxy mass plays a role in stopping star formation for nearby galaxies.
The number and luminosity distribution of white dwarfs stars can be used to help figure out the past history of the Galactic halo.