The stellar mass function and star formation rate-stellar mass relation
  of galaxies at z ~ 4 - 7
  We investigate the evolution of the star formation rate-stellar mass relation
(SFR-M*) and Galaxy Stellar Mass Function (GSMF) of z ~ 4-7 galaxies, using
cosmological simulations run with the smoothed particle hydrodynamics code
P-GADGET3(XXL). We explore the effects of different feedback prescriptions
(supernova driven galactic winds and AGN feedback), initial stellar mass
functions and metal cooling. We show that our fiducial model, with strong
energy-driven winds and early AGN feedback, is able to reproduce the observed
stellar mass function obtained from Lyman-break selected samples of star
forming galaxies at redshift 6 < z < 7. At z ~ 4, observed estimates of the
GSMF vary according to how the sample was selected. Our simulations are more
consistent with recent results from K-selected samples, which provide a better
proxy of stellar masses and are more complete at the high mass end of the
distribution. We find that in some cases simulated and observed SFR-M*
relations are in tension, and this can lead to numerical predictions for the
GSMF in excess of the GSMF observed. By combining the simulated SFR(M*)
relationship with the observed star formation rate function at a given
redshift, we argue that this disagreement may be the result of the uncertainty
in the SFR-M* (Luv-M*) conversion. Our simulations predict a population of
faint galaxies not seen by current observations.
