Quantifying scatter in galaxy formation at the lowest masses

Understand

We predict the stellar mass -- halo mass (SMHM) relationship for dwarf galaxies, using simulated galaxies with peak halo masses of M$_{\rm peak} = 10^{11}$ M$_{\odot}$ down into the ultra-faint dwarf range to M$_{\rm peak} =$ 10$^7$ M$_{\odot}$.

• Our simulated dwarfs have stellar masses of M$_{\rm star} = $ 790 M$_{\odot}$ to $8.2 \times 10^8$ M$_{\odot}$, with corresponding $V$-band magnitudes from $-2$ to $-18.5$.
• For M$_{\rm peak} > 10^{10}$ M$_{\odot}$, the simulated SMHM relationship agrees with literature determinations, including exhibiting a small scatter of 0.3 dex.
• However, the scatter in the SMHM relation increases for lower-mass halos.