LMC-driven anisotropic boosts in stream--subhalo interactions

Understand

Dark Matter (DM) subhalos are predicted to perturb stellar streams; stream morphologies and dynamics can constrain the mass distribution of subhalos.

• Using FIRE-2 simulations of Milky Way-mass galaxies, we show that presence of a Large Magellanic Cloud (LMC)--analog significantly changes stream-subhalo encounter rates.
• Three key factors drive these changes.
• First, the LMC--analog brings in many subhalos, increasing encounter rates for streams near the massive satellite by up to 20--40%.