Volume 647, March 2021
|Number of page(s)||24|
|Published online||25 March 2021|
The Fornax3D project: Assembly histories of lenticular galaxies from a combined dynamical and population orbital analysis
Research Centre for Astronomy, Astrophysics, and Astrophotonics, Department of Physics and Astronomy, Macquarie University, Macquarie Park, NSW 2109, Australia
2 European Southern Observatory, Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany
3 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, PR China
4 Department of Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180 Wien, Austria
5 INAF – Astronomical Observatory of Capodimonte, Salita Moiariello 16, 80131 Naples, Italy
6 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
7 Dipartimento di Fisica e Astronomia ‘G. Galilei’, Università di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
8 INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
9 Instituto de Astrofísica de Canarias, Calle Via Láctea s/n, 38200 La Laguna, Tenerife, Spain
10 Depto. Astrofísica, Universidad de La Laguna, Calle Astrofísico Francisco Sánchez s/n, 38206 La Laguna, Tenerife, Spain
11 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Straße 1, 85748 Garching bei München, Germany
12 Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK
13 Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
14 Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, 9000 Gent, Belgium
15 Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 RA Leiden, The Netherlands
16 Max-Planck-Institut für Extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching bei München, Germany
Accepted: 1 February 2021
In order to assess the impact of the environment on the formation and evolution of galaxies, accurate assembly histories of such galaxies are needed. However, these measurements are observationally difficult owing to the diversity of formation paths that lead to the same present-day state of a galaxy. In this work, we apply a powerful new technique in order to observationally derive accurate assembly histories through a self-consistent combined stellar dynamical and population galaxy model. We present this approach for three edge-on lenticular galaxies from the Fornax3D project – FCC 153, FCC 170, and FCC 177 – in order to infer their mass assembly histories individually and in the context of the Fornax cluster. The method was tested on mock data from simulations to quantify its reliability. We find that the galaxies studied here have all been able to form dynamically-cold (intrinsic vertical velocity dispersion σz ≲ 50 km s−1) stellar disks after cluster infall. Moreover, the pre-existing (old) high angular momentum components have retained their angular momentum (orbital circularity λz > 0.8) through to the present day. Comparing the derived assembly histories with a comparable galaxy in a low-density environment – NGC 3115 – we find evidence for cluster-driven suppression of stellar accretion and merging. We measured the intrinsic stellar age–velocity-dispersion relation and find that the shape of the relation is consistent with galaxies in the literature across redshift. There is tentative evidence for enhancement in the luminosity-weighted intrinsic vertical velocity dispersion due to the cluster environment. But importantly, there is an indication that metallicity may be a key driver of this relation. We finally speculate that the cluster environment is responsible for the S0 morphology of these galaxies via the gradual external perturbations, or ‘harassment’, generated within the cluster.
Key words: galaxies: kinematics and dynamics / galaxies: stellar content / galaxies: structure / galaxies: formation / galaxies: elliptical and lenticular, cD / galaxies: evolution
© ESO 2021
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