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Paper: Gas Accretion and Consumption in Disks in the Local Universe from the S4G/DAGAL Survey
Volume: 480, Structure and Dynamics of Disk Galaxies
Page: 221
Authors: Bouquin, A. Y. K.; Gil de Paz, A.; Boissier, S.; Muñoz-Mateos, J. C.
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 S4G Spitzer/IRAC-3.6 μm photometry. The analysis of the (FUV-NUV) vs. (NUV-[3.6]) color-color and (FUV-NUV) vs. M[3.6] color-magnitude diagrams (CMD) reveal both a narrow so-called “blue sequence”, where Irr through Sb's are located, and a “red cloud”, where E/S0 galaxies reside. This is opposite to the morphology seen in optical CMDs, and in the case of the color-color diagram, it reflects the degeneracy between SFH of disk galaxies and dust extinction (which strongly correlates the FUV-NUV and NUV-[3.6] colors) and could only be seen in its full extent thanks to the statistics and wide range of galaxy masses and types provided by S4G/DAGAL. We find that a large fraction (%) of the galaxies evolving off (or into) this “blue sequence” towards (or from) the “red cloud” are early-type spirals, 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, NUV-optical, or even NUV-[3.6]).
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