Is there a disk of satellites around the Milky Way?

Abstract

The "Disk of satellites" (DoS) around Milky Way is a highly debated topic with conflicting interpretations of observations and their theoretical models. We perform a comprehensive analysis of all dwarfs detected in the Milky Way and find that the DoS structure depends strongly on the plane identification method and the sample size. In particular, we demonstrate that a smaller sample size produces a higher anisotropy of the spatial distribution and a stronger clustering of the angular momentum of the satellites. Moreover, we calculate the evolution of the 11 classical satellites with proper motion measurements and find that the thin DoS they currently reside in is transient. Furthermore, we analyze two cosmological simulations using the same initial conditions of a Milky Way-sized galaxy, an N-body run with dark matter only and a hydrodynamic one with both baryonic and dark matter, and find that the hydrodynamic simulation produces more anisotropic distribution of satellites than the N-body one. Our results suggest that an anisotropic distribution of satellites in galaxies can originate from baryonic processes in the hierarchical structure formation model, but the claimed highly-flattened, coherently-rotating DoS of the Milky Way may be a small-number selection effect. These findings may help resolve the contradictory claims of DoS in other galaxies and the discrepancy among numerical simulations.

Published in ApJ. 7 pages, 5 figures

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Cited by in corpus (7)

• The Lopsidedness of Satellite Galaxy Systems in $\Lambda$CDM simulations
• ZOMG III: The effect of Halo Assembly on the Satellite Population
• The lopsided distribution of satellites of isolated central galaxies
• On the origin of the asymmetric dwarf galaxy distribution around Andromeda
• Planes of satellites around simulated disk galaxies II: Time-persistent planes of kinematically-coherent satellites in $\Lambda$CDM
• A Study of the Properties and Dynamics of the Disk of Satellites in a Milky-Way-like Galaxy System
• The long-term stability of the Vast Polar Structure and its connection to a possible previous passage of the LMC