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

Ding, Y, Martig, M ORCID: 0000-0001-5454-1492, Zhu, L, Fraser-McKelvie, A, Leaman, R, van de Ven, G, van de Sande, J, Pinna, F, Emsellem, E, Fragkoudi, F, Jin, Y, Poci, A, de Sa-Freitas, C, Frosst, M, Cai, R, Croom, SM, Davis, TA, Elliott, R, Hayden, MR, Falcon-Barroso, J et al (2026) The GECKOS survey: assembly history of the lenticular galaxy NGC 3957. Monthly Notices of the Royal Astronomical Society, 552 (1). ISSN 0035-8711

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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 baris a long-lived structure that formed at least ∼ 7 Gyr ago. The main stellar disc is dynamically cold (σz ∼ 20−30 km s−1), precluding any significant mergers over the last ∼ 8 Gyr, and exhibits a strong positive age gradient (younger inside, older outside) beyond the bar radius. Synthesizing 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 lenticular galaxies 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
Uncontrolled Keywords:	galaxies: elliptical and lenticular, cD; galaxies: evolution; galaxies: formation; galaxies: kinematics and dynamics; galaxies: structure; galaxies: elliptical and lenticular, cD; galaxies: evolution; galaxies: formation; galaxies: kinematics and dynamics; galaxies: structure; 5109 Space Sciences; 5107 Particle and High Energy Physics; 5101 Astronomical Sciences; 51 Physical Sciences; 0201 Astronomical and Space Sciences; Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press
Date of acceptance:	26 August 2026
Date of first compliant Open Access:	25 September 2026
Date Deposited:	25 Sep 2026 14:31
Last Modified:	25 Sep 2026 14:31
DOI or ID number:	10.1093/mnras/stag1634
URI:	https://researchonline.ljmu.ac.uk/id/eprint/29537

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