Kavli Affiliate: Mark Vogelsberger
| First 5 Authors: Hayden R. Foote, Gurtina Besla, Philip Mocz, Nicolás Garavito-Camargo, Lachlan Lancaster
| Summary:
The Large Magellanic Cloud (LMC) will induce a dynamical friction (DF) wake
on infall to the Milky Way (MW). The MW’s stellar halo will respond to the
gravity of the LMC and the dark matter (DM) wake, forming a stellar counterpart
to the DM wake. This provides a novel opportunity to constrain the properties
of the DM particle. We present a suite of high-resolution, windtunnel-style
simulations of the LMC’s DF wake that compare the structure, kinematics, and
stellar tracer response of the DM wake in cold DM (CDM), with and without
self-gravity, vs. fuzzy DM (FDM) with $m_a = 10^{-23}$ eV. We conclude that the
self-gravity of the DM wake cannot be ignored. Its inclusion raises the wake’s
density by $sim 10%$, and holds the wake together over larger distances
($sim$ 50 kpc) than if self-gravity is ignored. The DM wake’s mass is
comparable to the LMC’s infall mass, meaning the DM wake is a significant
perturber to the dynamics of MW halo tracers. An FDM wake is more granular in
structure and is $sim 20%$ dynamically colder than a CDM wake, but with
comparable density. The granularity of an FDM wake increases the stars’
kinematic response at the percent level compared to CDM, providing a possible
avenue of distinguishing a CDM vs. FDM wake. This underscores the need for
kinematic measurements of stars in the stellar halo at distances of 70-100 kpc.
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