Stellar Populations of Spectroscopically Decomposed Bulge–Disk for S0 Galaxies from the CALIFA Survey

Abstract

We investigate the stellar population properties of bulges and disks separately for 34 S0s using integral-field spectroscopy from the Calar Alto Legacy Integral Field Area survey. The spatially resolved stellar age and metallicity of bulge and disk components are simultaneously estimated using the penalized pixel fitting method with photometrically defined weights for the two components. We find a tight correlation between age and metallicity for bulges, while the relation for disks has a larger scatter than that for bulges. This implies that the star formation histories of disks are more complicated than those of bulges. The bulges of high-mass S0s are mostly comparable in terms of metallicity, while bulges appear to be systematically more metal-rich than disks for low-mass S0s. The ages of bulges and disks in high-mass S0s appear to increase with local density. The bulge ages of low-mass S0s also increase with local density, but such a trend is not clear in the disk ages of low-mass S0s. In addition, the age difference between bulge and disk components (ΔAge) tends to increase with local density, for both high-mass and low-mass S0s. High-mass S0s have systematically greater ΔAge than low-mass S0s at a given local density. Our results indicate that the stellar mass significantly influences the evolution of S0 galaxies, but the environment also plays an important role in determining the evolution of bulges and disks at a given stellar mass.