Structure, Kinematics, and Observability of the Large Magellanic Cloud’s Dynamical Friction Wake in Cold versus Fuzzy Dark Matter

• Published in: The Astrophysical journal Vol. 954; no. 2; pp. 163 - 190
• Main Authors: Foote, Hayden R., Besla, Gurtina, Mocz, Philip, Garavito-Camargo, Nicolás, Lancaster, Lachlan, Sparre, Martin, Cunningham, Emily C., Vogelsberger, Mark, Gómez, Facundo A., Laporte, Chervin F. P.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.09.2023; IOP Publishing
• Subjects: ASTRONOMY AND ASTROPHYSICS; Astrophysics; Cold dark matter; Dark matter; Density; Dynamical friction; Friction; Galactic halos; Kinematics; Large Magellanic Cloud; Magellanic clouds; Milky Way; Milky Way dark matter halo; Milky Way dynamics; Milky Way stellar halo; Tracers
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ace533

Abstract 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, versus 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 ∼10%, and holds the wake together over larger distances (∼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 ∼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 versus FDM wake. This underscores the need for kinematic measurements of stars in the stellar halo at distances of 70–100 kpc.