The link between the masses and central stellar populations of S0 galaxies

TL;DR

This study investigates the central stellar populations and dynamics of S0 galaxies in the Fornax Cluster, revealing that their properties are primarily driven by dynamical mass, age, and alpha-element abundance variations, with rotation playing a significant role.

Contribution

It provides new insights into the stellar population correlations in S0 galaxies, emphasizing the importance of rotational support and dynamical mass over metallicity in driving these relations.

Findings

Correlations between absorption-line indices and velocity dispersion are driven by age and alpha-element variations.

Tighter relations exist between line indices and maximum circular velocity, highlighting the role of dynamical mass.

More massive S0 galaxies have shorter star-formation timescales and older stellar populations.

Abstract

Using high signal-to-noise ratio VLT/FORS2 long-slit spectroscopy, we have studied the properties of the central stellar populations and dynamics of a sample of S0 galaxies in the Fornax Cluster. The central absorption-line indices in these galaxies correlate well with the central velocity dispersions (Sigma0) in accordance with what previous studies found for elliptical galaxies. However, contrary to what it is usually assumed for cluster ellipticals, the observed correlations seem to be driven by systematic age and alpha-element abundance variations, and not changes in overall metallicity. We also found that the observed scatter in the Index-Sigma0 relations can be partially explained by the rotationally-supported nature of these systems. Indeed, even tighter correlations exist between the line indices and the maximum circular velocity of the galaxies. This study suggests that the dynamical mass is the physical property driving these correlations, and for S0 galaxies such masses have to be estimated assuming a large degree of rotational support. The observed trends imply that the most massive S0s have the shortest star-formation timescales and the oldest stellar populations.