We analyse the stellar mass-to-light ratio (M/L) gradients in a large sample of local galaxies taken from the Sloan Digital Sky Survey, spanning a wide range of stellar masses and morphological types. As suggested by the well-known relationship between M/L values and colours, we show that M/L gradients are strongly correlated with colour gradients, which we trace to the effects of age variations. Stellar M/L gradients generally follow patterns of variation with stellar mass and galaxy type that were previously found for colour and metallicity gradients. In late-type galaxies M/L gradients are negative, steepening with increasing mass. In early-type galaxies M/L gradients are shallower, while presenting a twofold trend: they decrease with mass up to a characteristic mass of Graphic and increase at larger masses. We compare our findings with other analyses and discuss some implications for galaxy formation and for dark matter estimates.
C. Tortora, N. R. Napolitano, Aaron J. Romanowsky, Ph. Jetzer, V. F. Cardone, and M. Capaccioli. "Stellar mass-to-light ratio gradients in galaxies: correlations with mass" Monthly Notices of the Royal Astronomical Society (2011): 1557-1564. doi:10.1111/j.1365-2966.2011.19438.x