2013, Arkansas Talk Pre-registered talk title and abstract (as of April).

"Gas accretion and extended disks in the Local Universe from the S4G/DAGAL survey"

Abstract: 

We have obtained GALEX UV radial surface brightness and color profiles, as well as integrated magnitudes for +1500 galaxies covering ~70% of the S4G/DAGAL volume-limited sample of nearby galaxies (d<40Mpc), and combined these with Spitzer/IRAC-3.6um photometry. The analysis of the (FUV-NUV) vs (NUV-3.6um) color-color diagram reveals both a so-called "blue sequence", where Irr through Sb's are located, and a "red cloud", where E/S0 reside. This is opposite to the morphology seen in optical CMDs and it mostly due to the degeneracies between SFH of disk galaxies and dust extinction (which strongly correlates the FUV-NUV and NUV-3.6 colors) and could only be seen thanks to the statistics and wide range of galaxy masses and types provided by S4G/DAGAL. We find many early-type spirals evolving off (or into) this "blue sequence" towards (or from) the "red cloud" that we interpret as a sign of strangulation (or re-birth) of the star formation in these galaxies. Such processes lead to distinct FUV-NUV colors, as this color is very sensitive to recent changes in the star formation activity, compared to other colors (optical ones or even NUV-3.6).