New insights on the dynamics of satellite galaxies: Effects of the figure rotation of a host galaxy.

This article investigates the formation and long-term stability of the planar spatial distribution of satellite galaxies around the Milky Way (MW), known as the satellite plane, which poses a challenge to the standard ΛCDM cosmological model. Focusing on the figure rotation—rotation of the host galaxy's triaxial gravitational potential—the study finds that such rotation can induce a stable orbital plane perpendicular to the rotation axis, potentially explaining the observed satellite plane if the MW's dark halo rotates with its axis aligned near the plane's normal vector. The stability of this planar structure requires satellites to have a small velocity dispersion perpendicular to the plane relative to their mean rotational velocity; while not all MW satellites meet this condition, a subset identified as member satellites does. The authors suggest that the alignment of the figure rotation and satellite plane arises naturally from filamentary accretion of dark matter and group infall of satellites along cosmic filaments, providing a dynamical mechanism consistent with observations and cosmological structure formation.