The tidal features of the classical Milky Way satellites: Expected in MOND but inconsistent with cold dark matter models
Abstract
Most classical satellites of the Milky Way are known to display signs of tidal disturbance (e.g. tidal tails, substructures, and distorted shapes). This cannot be explained by the standard model of cosmology due to its prediction that the dark matter haloes of the classical satellites confer them with very strong self-gravity and make them resilient to the Milky Way's gravitational tides. In this work, we estimate the tidal susceptibility of the classical satellites by comparing their half-mass radius with their theoretical tidal radius at pericentre in both the standard model and in the Milgromian dynamics (MOND) model. With this approach, we demonstrate that most classical satellites are expected to be tidally perturbed in MOND, so their observed tidal features are generally in good agreement with MOND expectations. Since gravitational tides can also enhance the velocity dispersion of the satellites, we argue that MOND can plausibly explain the unusually high velocity dispersions reported for some of the classical satellites.
Versions
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BibTeX
@misc{asencio2026tidal,
title = {{The tidal features of the classical Milky Way satellites: Expected in MOND but inconsistent with cold dark matter models}},
author = {Elena Asencio and Indranil Banik and Pavel Kroupa},
howpublished = {arXiv},
year = {2026},
month = jul,
doi = {10.48550/arxiv.2607.05502},
eprint = {2607.05502},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.05502},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The tidal features of the classical Milky Way satellites: Expected in MOND but inconsistent with cold dark matter models
AU - Elena Asencio
AU - Indranil Banik
AU - Pavel Kroupa
PY - 2026
DA - 2026/07/06
PB - arXiv
DO - 10.48550/arxiv.2607.05502
UR - https://arxiv.org/abs/2607.05502
AB - Most classical satellites of the Milky Way are known to display signs of tidal disturbance (e.g. tidal tails, substructures, and distorted shapes). This cannot be explained by the standard model of cosmology due to its prediction that the dark matter haloes of the classical satellites confer them with very strong self-gravity and make them resilient to the Milky Way's gravitational tides. In this work, we estimate the tidal susceptibility of the classical satellites by comparing their half-mass radius with their theoretical tidal radius at pericentre in both the standard model and in the Milgromian dynamics (MOND) model. With this approach, we demonstrate that most classical satellites are expected to be tidally perturbed in MOND, so their observed tidal features are generally in good agreement with MOND expectations. Since gravitational tides can also enhance the velocity dispersion of the satellites, we argue that MOND can plausibly explain the unusually high velocity dispersions reported for some of the classical satellites.
ER -