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.
Citation
Moffett , A J , Phillipps , S , Robotham , A S G , Driver , S P , Bremer , M N , Cortese , L , Wong , O I , Brough , S , Brown , M J I , Bryant , J J , Conselice , C J , Croom , S M , George , K , Goldstein , G , Goodwin , M , Holwerda , B W , Hopkins , A M , Konstantopoulos , I S , Lawrence , J S , Lorente , N P F , Medling , A M , Owers , M S , Pimbblet , K A , Richards , S N , Sweet , S M & Van De Sande , J 2019 , ' Star-forming, rotating spheroidal galaxies in the GAMA and SAMI Surveys ' , Monthly Notices of the Royal Astronomical Society , vol. 489 , no. 2 , pp. 2830–2843 . https://doi.org/10.1093/mnras/stz2237
Publication
Monthly Notices of the Royal Astronomical Society
Status
Peer reviewed
ISSN
0035-8711Type
Journal article
Collections
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