Push it to the limit: Local Group constraints on high-redshift stellar mass functions for Mstar > 10^5 Msun

Understand

We constrain the evolution of the galaxy stellar mass function from 2 < z < 5 for galaxies with stellar masses as low as 10^5 Msun by combining star formation histories of Milky Way satellite galaxies derived from deep Hubble Space Telescope observations with merger trees from the ELVIS suite of N-body simulations.

• This approach extends our understanding more than two orders of magnitude lower in stellar mass than is currently possible by direct imaging.
• We find the faint end slopes of the mass functions to be alpha= -1.42(+0.07/-0.05) at z = 2 and alpha = -1.57^(+0.06/-0.06) at z = 5, and show the slope only weakly evolves from z = 5 to z = 0.
• Our findings are in stark contrast to a number of direct detection studies that suggest slopes as steep as alpha = -1.9 at these epochs.