paper

A whirling plane of satellite galaxies around Centaurus A challenges cold dark matter cosmology

arXiv:1802.00081 · doi:10.1126/science.aao1858

Abstract

The Milky Way and Andromeda galaxy are each surrounded by a thin plane of satellite galaxies that may be corotating. Cosmological simulations predict that most satellite galaxy systems are close to isotropic with random motions, so those two well-studied systems are often interpreted as rare statistical outliers. We test this assumption using the kinematics of satellite galaxies around the Centaurus A galaxy. Our statistical analysis reveals evidence for corotation in a narrow plane: of the 16 Centaurus A's satellites with kinematic data, 14 follow a coherent velocity pattern aligned with the long axis of their spatial distribution. In standard cosmology simulations, < 0.5% of Centaurus A-like systems show such behavior. Corotating satellite systems may be common in the Universe, challenging small-scale structure formation in the prevailing cosmological paradigm.

Published in the first Feb 2018 issue of Science (Müller et al., Science 359, 534, 2018). This preprint corresponds to the accepted and language edited version of the manuscript. 32 pages, 5 figures

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