The GECKOS survey: Assembly history of the lenticular galaxy NGC 3957

Ding, Y., Martig, M., Zhu, L., Fraser-McKelvie, A., Leaman, R. and Davis, T. A. ORCID: https://orcid.org/0000-0003-4932-9379 2026. The GECKOS survey: Assembly history of the lenticular galaxy NGC 3957. Monthly Notices of the Royal Astronomical Society , stag1634. 10.1093/mnras/stag1634

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Abstract

We analyse the assembly history of the edge-on lenticular galaxy NGC 3957 using deep integral-field spectroscopic MUSE data from the GECKOS survey. By applying a dust-corrected Multi-Gaussian Expansion and a population-orbit superposition model, we disentangle the galaxy’s stellar kinematics, age, and metallicity. We dynamically decompose the galaxy and identify three distinct components: a dynamically-cold main disc, a compact Nuclear Stellar Disc (NSD), and a hot component. The NSD emerges as the youngest and most metal-rich component (t = 6.9 ± 0.4 Gyr; [Z/H] = 0.49 ± 0.06 dex), implying that the stellar bar is a long-lived structure that formed at least ~7 Gyr ago. The main stellar disc is dynamically cold (σz ~ 20 − 30 km/s), precluding any significant mergers over the last ~8 Gyr, and exhibits a strong positive age gradient (younger inside, older outside) beyond the bar radius. Synthesising these dynamical fossil records, NGC 3957 likely evolved as a ‘faded spiral’ in a small-to-medium group environment. Its outer disc might passively fade due to mild gas starvation, while the bar fuelled prolonged central star formation. Comparison with S0s in the Fornax cluster reveals that this combination of internal secular evolution and mild starvation produces ‘outside-in’ fading signatures that could mimic the environmental stripping typically seen in dense clusters.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Physical, Chemical & Environmental Sciences Schools > Physics and Astronomy
Additional Information:	For the complete author list please see https://doi.org/10.1093/mnras/stag1634
Publisher:	Oxford University Press
ISSN:	0035-8711
Date of First Compliant Deposit:	10 September 2026
Last Modified:	10 Sep 2026 13:45
URI:	https://orca.cardiff.ac.uk/id/eprint/189530

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