Evolution of dwarf early-type galaxies I. Spatially resolved stellar populations and internal kinematics of Virgo cluster dE/dS0 galaxies

Abstract

Understanding the origin and evolution of dwarf early-type galaxies remains an important open issue in modern astrophysics. Internal kinematics of a galaxy contains signatures of violent phenomena which may have occurred, e.g. mergers or tidal interactions, while stellar population keeps a fossil record of the star formation history, therefore studying connection between them becomes crucial for understanding galaxy evolution. Here, in the first paper of the series, we present the data on spatially resolved stellar populations and internal kinematics for a large sample of dwarf elliptical (dE) and lenticular (dS0) galaxies in the Virgo cluster. We obtained radial velocities, velocity dispersions, stellar ages and metallicities out to 1--2 half-light radii by re-analysing already published long-slit and integral-field spectroscopic datasets using the {\sc NBursts} full spectral fitting technique. Surprisingly, bright representatives of the dE/dS0 class ($M_B=-\mathrm{18.0...}-16.0$ mag) look very similar to intermediate-mass and giant lenticulars and ellipticals: (1) their nuclear regions often harbour young metal-rich stellar populations always associated with the drops in the velocity dispersion profiles; (2) metallicity gradients in the main discs/spheroids vary significantly from nearly flat profiles to -0.9 dex $r_e^{-1}$, i.e. somewhat 3 times steeper than for typical bulges; (3) kinematically decoupled cores were discovered in 4 galaxies, including two with very little, if any, large scale rotation. These results suggest similarities in the evolutionary paths of dwarf and giant early-type galaxies and call for reconsidering the role of major mergers in the dE/dS0 evolution.

22 pages, 3 tables, 29 figures, accepted to MNRAS

References in corpus (10)

• The origin of dwarf ellipticals in the Virgo cluster
• Spectroscopic ages and metallicities of stellar populations: validation of full spectrum fitting
• Kinematics and stellar populations of the dwarf elliptical galaxy IC 3653
• The relation between stellar populations, structure and environment for dwarf elliptical galaxies from the MAGPOP-ITP
• Virgo cluster early-type dwarf galaxies with the Sloan Digital Sky Survey. IV. The color-magnitude relation
• The origin of the mu_e - M_B and Kormendy relations in dwarf elliptical galaxies
• Kinematics and Stellar Populations of Low-Luminosity Early-Type Galaxies in the Abell 496 Cluster
• Stellar Population Constraints on the Dark Matter Content and Origin of Ultra-Compact Dwarf Galaxies
• Towards a Solution for the Ca II Triplet Puzzle : Results from Dwarf Elliptical Galaxies
• Formation and Evolution of Dwarf Elliptical Galaxies