The Milky Way's plane of satellites: consistent with $\Lambda$CDM
Abstract
The "plane of satellites problem" describes the arrangement of the Milky Way's 11 brightest satellite galaxies in a remarkably thin plane, possibly supported by rotation. This is in apparent contradiction to the standard cosmological model, wherein the Galaxy is surrounded by a dispersion-supported dark matter halo. Here, we show that the reported exceptional anisotropy of the satellite system is strongly contingent on a lopsided radial distribution, which earlier simulations have failed to reproduce, combined with the close but fleeting conjunction of the two most distant satellites, Leo I and Leo II. Using Gaia proper motions, we show that the orbital pole alignment is much more common than previously reported, and reveal the plane of satellites to be transient rather than rotationally supported. Comparing to new simulations, where such short-lived planes are common, we find the Milky Way satellites to be compatible with standard model expectations.
Cite
@article{arxiv.2205.02860,
title = {The Milky Way's plane of satellites: consistent with $\Lambda$CDM},
author = {Till Sawala and Marius Cautun and Carlos S. Frenk and John Helly and Jens Jasche and Adrian Jenkins and Peter H. Johansson and Guilhem Lavaux and Stuart McAlpine and Matthieu Schaller},
journal= {arXiv preprint arXiv:2205.02860},
year = {2022}
}