Dissecting early-type dwarf galaxies into their multiple components

TL;DR

This study uses advanced two-dimensional decomposition to reveal the complex structures of early-type dwarf galaxies in the Virgo cluster, identifying multiple components and features like bars and lenses that were previously undetected.

Contribution

First application of 2D multi-component decomposition to early-type dwarf galaxies, uncovering diverse structures and higher complexity than prior single-component analyses.

Findings

Only 25% of galaxies are single Sersic systems.

Bar fraction among the sample is 18%.

Lenses are detected as shallow structures with sharp edges.

Abstract

Early-type dwarf galaxies, once believed to be simple systems, have recently been shown to exhibit an intriguing diversity in structure and stellar content. To analyze this further, we started the SMAKCED project, and obtained deep H-band images for 101 early-type dwarf galaxies in the Virgo cluster in a brightness range of -19 \leq M_r \leq -16 mag, typically reaching a signal-to-noise of 1 per pixel of \sim0.25" at surface brightnesses \sim22.5 mag/arcsec^2 in the H-band. Here we present the first results of decomposing their two-dimensional light distributions. This is the first study dedicated to early-type dwarf galaxies using the two-dimensional multi-component decomposition approach, which has been proven to be important for giant galaxies. Armed with this new technique, we find more structural components than previous studies: only a quarter of the galaxies fall into the simplest group, namely those represented by a single S\'ersic function, optionally with a nucleus. Furthermore, we find a bar fraction of 18%. We detect also a similar fraction of lenses which appear as shallow structures with sharp outer edges. Galaxies with bars and lenses are found to be more concentrated towards the Virgo galaxy center than the other sample galaxies.