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The Fornax3D project: intrinsic correlations between orbital properties and the stellar initial mass function

Poci, A; McDermid, RM; Lyubenova, M; Martín-Navarro, I; van de Ven, G; Coccato, L; Corsini, EM; Fahrion, K; Falcón-Barroso, J; Gadotti, DA; Iodice, E; Pinna, F; Sarzi, M; de Zeeuw, PT; Zhu, L

The Fornax3D project: intrinsic correlations between orbital properties and the stellar initial mass function Thumbnail


RM McDermid

M Lyubenova

I Martín-Navarro

G van de Ven

L Coccato

EM Corsini

K Fahrion

J Falcón-Barroso

DA Gadotti

E Iodice

F Pinna

M Sarzi

PT de Zeeuw

L Zhu


Variations of the stellar initial mass function (IMF) in external galaxies have been inferred from a variety of independent probes. Yet the physical conditions causing these variations remain largely unknown. In this work, we explore new spatially resolved measurements of the IMF for three edge-on lenticular galaxies in the Fornax cluster. We utilize existing orbit-based dynamical models in order to fit the new IMF maps within an orbital framework. We find that, within each galaxy, the high-angular momentum disc-like stars exhibit an IMF which is rich in dwarf stars. The centrally concentrated pressure-supported orbits exhibit similarly dwarf-rich IMF. Conversely, orbits at large radius which have intermediate angular momentum exhibit IMF which are markedly less dwarf-rich relative to the other regions of the same galaxy. Assuming that the stars which reside, in the present-day, on dynamically hot orbits at large radii are dominated by accreted populations, we interpret these findings as a correlation between the dwarf-richness of a population of stars, and the mass of the host in which it formed. Specifically, deeper gravitational potentials would produce more dwarf-rich populations, resulting in the relative deficiency of dwarf stars which originated in the lower mass accreted satellites. The central and high-angular momentum populations are likely dominated by in situ stars, which were formed in the more massive host itself. There are also global differences between the three galaxies studied here, of up to ∼0.3 dex in the IMF parameter ξ. We find no local dynamical or chemical property which alone can fully account for the IMF variations.


Poci, A., McDermid, R., Lyubenova, M., Martín-Navarro, I., van de Ven, G., Coccato, L., …Zhu, L. (2022). The Fornax3D project: intrinsic correlations between orbital properties and the stellar initial mass function. Monthly Notices of the Royal Astronomical Society, 514(3), 3660-3669.

Journal Article Type Article
Acceptance Date May 25, 2022
Online Publication Date Jun 7, 2022
Publication Date 2022
Deposit Date Jul 14, 2022
Publicly Available Date Jul 14, 2022
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 514
Issue 3
Pages 3660-3669


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Copyright Statement
© The Author(s) 2022.<br /> Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative<br /> Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium,<br /> provided the original work is properly cited

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