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

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.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2026-09-01
DOI
https://doi.org/10.1093/mnras/stag1634
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
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article

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

Amelia Fraser-McKelvie, Lucas M. Valenzuela, Antonino Marasco, Tayyaba Zafar et al.
Monthly Notices of the Royal Astronomical Society
Galaxies: Formation, Evolution, Phenomena
article

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

Amelia Fraser-McKelvie, Lucas M. Valenzuela, Antonino Marasco, Tayyaba Zafar, Francesca Fragkoudi, Meng Yang, Matthew Frosst, Timothy A. Davis, Dimitri Alexei Gadotti, S. M. Croom, Adriano Poci, Marie Martig, Emily Wisnioski, Zhu Ling, Yuchen Ding, R Elliott, J van de Sande, Z Wang (Purmortal), E Emsellem, F Pinna, R Leaman, M R Hayden, G van de Ven, J Falcón-Barroso, R Cai, C de Sá-Freitas, Y Jin
article en

Abstract

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.

Monthly Notices of the Royal Astronomical Society
Université Claude Bernard Lyon 1 (FR), École Normale Supérieure de Lyon (FR), Australian National University (AU), Centre National de la Recherche Scientifique (FR), The University of Sydney (AU), University of Vienna (AT), European Southern Observatory (DE), Universidad de La Laguna (ES), The University of Western Australia (AU), Durham University (GB), University of Utah (US), Shanghai Astronomical Observatory (CN), Mount Stromlo Observatory (AU), Westlake University (CN), UNSW Sydney (AU), University of Oxford (GB), Centre de Recherche Astrophysique de Lyon (FR), Instituto de Astrofísica de Canarias (ES), Osservatorio Astronomico di Padova (IT), International Centre for Radio Astronomy Research (AU), University of Chinese Academy of Sciences (CN), Swinburne University of Technology (AU), Liverpool John Moores University (GB), Cardiff University (GB), Ludwig-Maximilians-Universität München (DE), University of Oklahoma (US), Macquarie University (AU)
National Natural Science Foundation of China, Liverpool John Moores University, Ministerio de Ciencia e Innovación, Science and Technology Facilities Council
Openalex Percentile: Top 11%
Galaxies: Formation, Evolution, Phenomena
DOIOpen Access PDFOpenAlex
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