Metallicity Gradients - Mass Dependency in Dwarf Elliptical Galaxies

TL;DR

This study investigates the mass dependence of metallicity gradients in dwarf elliptical galaxies, finding consistent gradients but conflicting results with previous studies on the correlation between metallicity and galaxy mass.

Contribution

It provides a detailed analysis of metallicity and abundance gradients, addressing discrepancies in prior research and examining potential biases affecting gradient measurements.

Findings

Detected well above analysis biases metallicity gradients around -0.4 dex/r_e

Found moderate Mg/Fe abundance gradients in dwarf ellipticals

Identified unresolved discrepancy between different galaxy samples

Abstract

The formation and evolution of galaxies is imprinted on their stellar population radial gradients. Two recent articles present conflicting results concerning the mass dependence of the metallicity gradients for early-type dwarf galaxies. On one side, Spolaor et al. show a tight positive correlation between the total metallicity, Z/H and the mass. On the other side, in a distinct sample, we do not find any trend involving Fe/H (Koleva et al.). In order to investigate the origin of the discrepancy, we examine various factors that may affect the determination of the gradients: namely the sky subtraction and the signal-to-noise ratio. We conclude that our detection of gradients are well above the possible analysis biases. Then, we measured the Mg/Fe relative abundance profile and found moderate gradients. The derived Z/H gradients scatter around -0.4 dex/r_e. The two samples contain the same types of objects and the reason of the disagreement is still not understood. Based on observations made with ESO telescopes at La Silla Paranal observatory under program ID076.B-0196.