In situ globular clusters in alternative dark matter Milky Way galaxies: A first approach to fuzzy and core-like dark matter theories

LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS, 92190 Meudon, France

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Received: 15 October 2025
Accepted: 4 February 2026

Abstract

We present a first analysis of the dynamics of in situ globular clusters (GCs) in Milky Way (MW)-like galaxies embedded in fuzzy dark matter (FDM) halos, combining cosmological assembly histories from the TNG50 simulation with dedicated orbital integrations and analytical models. GC populations were initialized with identical distributions in normalized E-L_z in matched cold dark matter (CDM) and FDM halos. In a universe dominated by FDM, we identified three distinct regimes for the in situ GC population depending on the particle mass m₂₂ ≡ m_χ/10⁻²² eV. For m₂₂ < 7, baryons dominate the inner potential, which remains steep and centrally concentrated, confining GC orbits to a narrow region and producing less massive, more compact systems than in CDM. For m₂₂ ∼ 7, GC properties resemble those in CDM, with similar mass and spatial distributions. For m₂₂ > 7, the dark matter becomes both compact and globally dominant, generating a deeper and more extended gravitational potential that supports a wider range of stable GC orbits, resulting in more massive and spatially extended GC systems. Finally, we extended our framework to make predictions for GC populations in alternative dark matter models, including warm dark matter and self-interacting dark matter, in both MW-like and dwarf galaxies. Our findings demonstrate that in situ GC systems offer a sensitive and independent probe of the underlying DM physics, opening new avenues for observational constraints with the upcoming Euclid mission.