Sweating the small stuff: simulating dwarf galaxies, ultra-faint dwarf galaxies, and their own tiny satellites

Understand

We present FIRE/Gizmo hydrodynamic zoom-in simulations of isolated dark matter halos, two each at the mass of classical dwarf galaxies ($M_{\rm vir} \simeq 10^{10} M_{\odot}$) and ultra-faint galaxies ($M_{\rm vir} \simeq 10^9 M_{\odot}$), and with two feedback implementations.

• The resultant central galaxies lie on an extrapolated abundance matching relation from $M_{\star} \simeq 10^6$ to $10^4 M_{\odot}$ without a break.
• Every host is filled with subhalos, many of which form stars.
• Our dwarfs with $M_{\star} \simeq 10^6 M_{\odot}$ each have 1-2 well-resolved satellites with $M_{\star} = 3-200 \times 10^3 M_{\odot}$.