z~4-10 galaxies from HST legacy fields

Our new LF determinations at z~4 and z~5 span a 6 mag baseline and reach to -16 AB mag. These determinations agree well with previous estimates, but the larger samples and volumes probed here result in a more reliable sampling of >L_{star}_ galaxies and allow us to reassess the form of the UV LFs. Our new LF results strengthen our earlier findings to 3.4{sigma} significance for a steeper faint-end slope of the UV LF at z>4, with {alpha} evolving from {alpha}=-1.64+/-0.04 at z~4 to {alpha}=-2.06+/-0.13 at z~7 (and {alpha}=-2.02+/-0.23 at z~8), consistent with that expected from the evolution of the halo mass function.

We find less evolution in the characteristic magnitude M^*^ from z~7 to z~4 the observed evolution in the LF is now largely represented by changes in {phi}_{star}_. No evidence for a non-Schechter-like form to the z~4-8 LFs is found. A simple conditional LF model based on halo growth and evolution in the M/L ratio ({alpha}(1+z}^-1.5^) of halos provides a good representation of the observed evolution.