Did the Milky Way dwarf satellites enter the halo as a group?

TL;DR

This paper investigates whether the Milky Way's dwarf satellites could have entered the halo as a group, analyzing dwarf associations and their structures to understand satellite distribution origins.

Contribution

It provides an analysis of dwarf galaxy associations' sizes and structures, assessing their role as progenitors of the Milky Way's satellite system.

Findings

Dwarf associations are too extended to explain satellite distributions.

A minor filamentary structure may relate to satellite infall directions.

Associations are located perpendicular to the supergalactic plane.

Abstract

The dwarf satellite galaxies in the Local Group are generally considered to be hosted in dark matter subhalos that survived the disruptive processes during infall onto their host halos. It has recently been argued that if the majority of satellites entered the Milky Way halo in a group rather than individually, this could explain the spatial and dynamical peculiarities of its satellite distribution. Such groups were identified as dwarf galaxy associations that are found in the nearby Universe. In this paper we address the question whether galaxies in such associations can be the progenitors of the Milky Way satellite galaxies. We find that the dwarf associations are much more extended than would be required to explain the disk-like distribution of the Milky Way and Andromeda satellite galaxies. We further identify a possible minor filamentary structure, perpendicular to the supergalactic plane, in which the dwarf associations are located, that might be related to the direction of infall of a progenitor galaxy of the Milky Way satellites, if they are of tidal origin.