Star-Forming, Rotating Spheroidal Galaxies in the GAMA and SAMI Surveys

Abstract

The Galaxy And Mass Assembly (GAMA) survey has morphologically identified a class of "Little Blue Spheroid" (LBS) galaxies whose relationship to other classes of galaxies we now examine in detail. Considering a sample of 868 LBSs, we find that such galaxies display similar but not identical colours, specific star formation rates, stellar population ages, mass-to-light ratios, and metallicities to Sd-Irr galaxies. We also find that LBSs typically occupy environments of even lower density than those of Sd-Irr galaxies, where ~65% of LBS galaxies live in isolation. Using deep, high-resolution imaging from VST KiDS and the new Bayesian, two-dimensional galaxy profile modeling code PROFIT, we further examine the detailed structure of LBSs and find that their Sérsic indices, sizes, and axial ratios are compatible with those of low-mass elliptical galaxies. We then examine SAMI Galaxy survey integral field emission line kinematics for a subset of 62 LBSs and find that the majority (42) of these galaxies display ordered rotation with the remainder displaying disturbed/non-ordered dynamics. Finally, we consider potential evolutionary scenarios for a population with this unusual combination of properties, concluding that LBSs are likely formed by a mixture of merger and accretion processes still recently active in low-redshift dwarf populations. We also infer that if LBS-like galaxies were subjected to quenching in a rich environment, they would plausibly resemble cluster dwarf ellipticals.

15 pages, 14 figures, MNRAS accepted

References in corpus (22)

• A simple model to interpret the ultraviolet, optical and infrared emission from galaxies
• The SAURON project -- IX. A kinematic classification for early-type galaxies
• Galaxy Zoo 1 : Data Release of Morphological Classifications for nearly 900,000 galaxies
• Compaction and Quenching of High-z Galaxies in Cosmological Simulations: Blue and Red Nuggets
• The SAMI Galaxy Survey: instrument specification and target selection
• The SAMI Galaxy Survey: Revisiting Galaxy Classification Through High-Order Stellar Kinematics
• Galaxy And Mass Assembly (GAMA): ${\mathcal{M}}_{\star }-R_{\mathrm{e}}$ relations of $z=0$ bulges, discs and spheroids
• ProFit: Bayesian Profile Fitting of Galaxy Images
• The SAMI Galaxy Survey: Spatially Resolving the Main Sequence of Star Formation
• Galaxy And Mass Assembly (GAMA): Refining the Local Galaxy Merger Rate using Morphological Information
• LZIFU: an emission-line fitting toolkit for integral field spectroscopy data
• The SAMI Galaxy Survey: Towards a unified dynamical scaling relation for galaxies of all types
• The SAURON Project - XIV. No escape from V${}_{\mathrm{esc}}$: a global and local parameter in early-type galaxy evolution
• The SAMI Galaxy Survey: Data Release One with Emission-line Physics Value-Added Products
• The SAMI Galaxy Survey: Revising the Fraction of Slow Rotators in IFS Galaxy Surveys
• Galaxy And Mass Assembly (GAMA): the Stellar Mass Budget of Galaxy Spheroids and Disks
• The HI Chronicles of LITTLE THINGS BCDs II: The Origin of IC 10's HI Structure
• Implications for the origin of dwarf early-type galaxies: a detailed look at the isolated rotating dwarf early-type galaxy CG 611, with ramifications for the Fundamental Plane's (S_K)^2 kinematic scaling and the spin-ellipticity diagram
• Structural analysis of star-forming blue early-type galaxies: Merger-driven star formation in elliptical galaxies
• Galaxy And Mass Assembly (GAMA): Blue spheroids within 87 Mpc
• On the origin of bursts in blue compact dwarf galaxies: clues from kinematics and stellar populations
• Galaxy And Mass Assembly (GAMA): The unimodal nature of the dwarf galaxy population

Cited by in corpus (10)

• Star-forming early- and quiescent late-type galaxies in the local Universe
• ProFuse: Physical Multi-Band Structural Decomposition of Galaxies and the Mass-Size-Age Plane
• The colors of bulges and disks in the core and outskirts of galaxy clusters
• Gems of the Galaxy Zoos -- a Wide-Ranging Hubble Space Telescope Gap-Filler Program
• Relaxed blue ellipticals: accretion-driven stellar growth is a key evolutionary channel for low mass elliptical galaxies
• Decoding NGC 7252 as a blue elliptical galaxy
• UV and NIR size of the low-mass field galaxies: the UV compact galaxies
• Deep optical imaging of star-forming blue early-type galaxies: Color map structures and faint features indicative of recent mergers
• Identification and Quenching of Nugget Galaxies in the RESOLVE Survey at z = 0
• Galaxy And Mass Assembly (GAMA): The Dependence of Star Formation on Surface Brightness in Low Redshift Galaxies