Revealing velocity dispersion as the best indicator of a galaxy's color, compared to stellar mass, surface mass density, or morphology

Wake, David A.; van Dokkum, Pieter G. and Franx, Marijn (2012). Revealing velocity dispersion as the best indicator of a galaxy's color, compared to stellar mass, surface mass density, or morphology. Astrophysical Journal Letters, 751(2), article no. L44.

DOI: https://doi.org/10.1088/2041-8205/751/2/L44

Abstract

Using data of nearby galaxies from the Sloan Digital Sky Survey we investigate whether stellar mass (M_star), central velocity dispersion (σ), surface mass density (Σ), or the Sérsic n parameter is best correlated with a galaxy’s rest-frame color. Specifically, we determine how the mean color of galaxies varies with one parameter when another is fixed. When M_star is fixed we see that strong trends remain with all other parameters, whereas residual trends are weaker when Σ, n, or σ is fixed. Overall σ is the best indicator of a galaxy’s typical color, showing the largest residual color dependence when any of the other three parameters are fixed, and M_star is the poorest. Other studies have indicated that both the central black hole mass and possibly host dark matter halo properties (mass or concentration) are also better correlated with σ than with M_star, Σ, or n. Therefore, it could be the case that the strong correlation between color and σ reflects an underlying relationship between a galaxy’s star formation history and/or present star formation rate and the properties of its dark matter halo and/or the feedback from its central supermassive black hole.

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