Kavli Affiliate: Lina Necib
| First 5 Authors: Nora Shipp, Alexander H. Riley, Christine M. Simpson, Rebekka Bieri, Lina Necib
| Summary:
Galaxies like the Milky Way are surrounded by complex populations of
satellites at all stages of tidal disruption. In this paper, we present a
dynamical study of the disrupting satellite galaxies in the Auriga simulations
that are orbiting 28 distinct Milky Way-mass hosts across three resolutions. We
find that the satellite galaxy populations are highly disrupted. The majority
of satellites that remain fully intact at present day were accreted recently
without experiencing more than one pericentre ($n_{rm peri} lesssim 1$) and
have large apocentres ($r_{rm apo} gtrsim 200$ kpc) and pericentres ($r_{rm
peri} gtrsim 50$ kpc). The remaining satellites have experienced significant
tidal disruption and, given full knowledge of the system, would be classified
as stellar streams. We find stellar streams in Auriga across the range of
pericentres and apocentres of the known Milky Way dwarf galaxy streams and,
interestingly, overlapping significantly with the Milky Way intact satellite
population. We find no significant change in satellite orbital distributions
across resolution. However, we do see substantial halo-to-halo variance of
$(r_text{peri}, r_text{apo})$ distributions across host galaxies, as well as
a dependence of satellite orbits on host halo mass – systems disrupt at larger
pericentres and apocentres in more massive hosts. Our results suggest that
either cosmological simulations (including, but not limited to, Auriga) are
disrupting satellites far too readily, or that the Milky Way’s satellites are
more disrupted than current imaging surveys have revealed. Future observing
facilities and careful mock observations of these systems will be key to
revealing the nature of this apparent discrepancy.
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