Stellar mass functions of galaxies to z=4

Comparisons of the K_s_-selected star-forming galaxy SMFs with UV-selected SMFs at 2.5<z<4 show reasonable agreement and suggest that UV-selected samples are representative of the majority of the stellar mass density at z>3.5. We estimate the average mass growth of individual galaxies by selecting galaxies at fixed cumulative number density. The average galaxy with log(M_star_/M_{sun}_)=11.5 at z=0.3 has grown in mass by only 0.2dex (0.3dex) since z=2.0 (3.5), whereas those with log(M_star_/M_{sun}_)=10.5 have grown by >1.0dex since z=2.

At z<2, the time derivatives of the mass growth are always larger for lower-mass galaxies, which demonstrates that the mass growth in galaxies since that redshift is mass-dependent and primarily bottom-up. Lastly, we examine potential sources of systematic uncertainties in the SMFs and find that those from photo-z templates, stellar population synthesis modeling, and the definition of quiescent galaxies dominate the total error budget in the SMFs.