Understanding the origin of early-type dwarfs: The spectrophotometric study of CGCG014-074

TL;DR

This study provides a detailed spectrophotometric analysis of the dwarf galaxy CGCG014-074, revealing its complex structure and stellar populations, which offer insights into the origins and evolution of early-type dwarf galaxies in various environments.

Contribution

It presents the first comprehensive spectrophotometric analysis of CGCG014-074, highlighting its unique features and evolutionary history, challenging existing theories about dwarf galaxy formation.

Findings

CGCG014-074 has a rotating inner disk and boxy isophotes.

The galaxy's nucleus is old and metal-poor, while the disk is younger and more metal-rich.

It likely represents a passive evolved building block galaxy.

Abstract

Early-type dwarf galaxies constitute a prevalent population in the central regions of rich groups and clusters in the local Universe. These low-luminosity and low-mass stellar systems play a fundamental role in the assembly of the luminous galaxies observed today, according to the $\Lambda$CDM hierarchical theory. The origin of early-type dwarfs has been linked to the transformation of disk galaxies interacting with the intracluster medium, especially in dense environments. However, the existence of low-luminosity early-type galaxies in low-density environments presents a challenge to this scenario. This study presents a comprehensive photometric and spectroscopic analysis of the early-type dwarf galaxy CGCG014-074 using deep GEMINI+GMOS data, focusing on its peculiarities and evolutionary implications. CGCG014-074 exhibits distinct features, including a rotating inner disk, an extended stellar formation with a quiescent phase since about 2 Gyr ago, and the presence of boxy isophotes. From the kinematic analysis, we confirm CGCG014-074 as a nucleated early-type dwarf galaxy with embedded disk. The study of its stellar population parameters using different methods provides significant insights into the galaxy's evolutionary history. These results show an old and metal-poor nucleus ($\sim 9.3$ Gyr and $\mathrm{[Z/H]}\sim-0.84$ dex), while the stellar disk is younger ($\sim4.4$ Gyr) with a higher metallicity ($\mathrm{[Z/H]}\sim-0.40$ dex). These distinctive features collectively position CGCG014-074 as a likely building block galaxy that has evolved passively throughout its history.