Stellar population gradients in early-type cluster galaxies with VIMOS IFU

TL;DR

This study investigates radial stellar population gradients in early-type galaxies within a cluster, revealing mostly flat age and alpha-abundance trends but significant negative metallicity gradients, with these gradients linked to central properties.

Contribution

It provides new measurements of stellar population gradients in early-type cluster galaxies using IFU data, highlighting their relation to central galaxy properties.

Findings

Galaxies show flat age and [alpha/Fe] gradients.

Negative metallicity gradients are common.

Gradients correlate with central stellar population properties.

Abstract

We present results from a pilot study of radial stellar population trends in early-type galaxies using the VLT VIMOS integral field unit (IFU). We observe twelve galaxies in the cluster Abell 3389 (z~0.027). For each galaxy, we measure 22 line-strength indices in multiple radial bins out to at least the effective radius. We derive stellar population parameters using a grid inversion technique, and calculate the radial gradients in age, metallcity and alpha-abundance. Generally, the galaxies in our sample have flat radial trends in age and [alpha/Fe], but negative gradients in [Z/H] (-0.20 +/- 0.05 dex). Combining our targets with two similar, long-slit studies to increase sample size, we find that the gradients are not correlated with the central velocity dispersion or K-band luminosity (both proxies for galaxy mass). However, we find that the age and metallicity gradients are both anti-correlated with their respective central values (to > 4 sigma), such that galaxies with young cores have steeper positive age gradients, and those with metal-rich centres have strong negative [Z/H] gradients.