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Angular momentum and orbits of Milky Way dwarf galaxies

Published online by Cambridge University Press:  30 October 2025

Hefan Li Open the ORCID record for Hefan Li [Opens in a new window] ,
Francois Hammer ,
Carine Babusiaux  and
Marcel S. Pawlowski
Hefan Li*
Affiliation:
Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Beijing, China
Francois Hammer
Affiliation:
GEPI, Observatoire de Paris, Université PSL, CNRS, Place Jules Janssen 92195, Meudon, France
Carine Babusiaux
Affiliation:
GEPI, Observatoire de Paris, Université PSL, CNRS, Place Jules Janssen 92195, Meudon, France Université de Grenoble-Alpes, CNRS, IPAG, F-38000 Grenoble, France
Marcel S. Pawlowski
Affiliation:
Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam Germany
*
email: lihf@bao.ac.cn
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Abstract

We calculated the positions and velocities of 47 dwarf galaxies using a Bayesian approach. Their angular momentum distribution shows that between 36% and 57% of the dwarf galaxies are located in the Vast Polar Structure (VPOS), which could conflict with expectations for a cosmological infall of primordial dwarfs. Using four gravitational potential models with mass spans from 2.8 × 1011 M⊙ to 15 × 1011 M⊙, we find that dwarf galaxies are over-concentrated near their pericenters compared to what Kepler’s law would expect. This suggests that there may be a large number of dwarf galaxies that have not yet been discovered, or that they are not satellites of the Milky Way.

Keywords

galaxies: dwarfgalaxies: kinematics and dynamics

Information

Type
Contributed Paper
Information
Proceedings of the International Astronomical Union , Volume 19 , Symposium S379: Dynamical Masses of Local Group Galaxies , December 2023 , pp. 19 - 24
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Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of International Astronomical Union

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