Linear Response of Rotating and Flattened Stellar Clusters: The Oblate Kuzmin–Kutuzov Stäckel Family

This paper investigates the linear response of a series of spheroidal stellar clusters, the Kuzmin–Kutuzov Stäackel family, which exhibit a continuous range of flattening and rotation, extending from an isochrone sphere to a Toomre disk. The method successfully replicates the growing modes previousl...

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Bibliographic Details
Main Authors: Kerwann Tep, Christophe Pichon, Michael S. Petersen
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/add5e5
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Summary:This paper investigates the linear response of a series of spheroidal stellar clusters, the Kuzmin–Kutuzov Stäackel family, which exhibit a continuous range of flattening and rotation, extending from an isochrone sphere to a Toomre disk. The method successfully replicates the growing modes previously identified in published N -body simulations. It relies on the efficiency of the matrix method to quantify systematically the effects of rotation and flattening on the eigenmodes of the galaxy. We identify two types of bisymmetric instabilities for the flatter models—the so-called bending and bar-growing modes—the latter of which persists even for very round models. As anticipated, in its least unstable configurations, the system becomes flatter as its rotational speed increases. More realistic equilibria will be required to achieve a better match to the main sequence of fast–slow rotators. The corresponding code is made public.
ISSN:1538-4357