UV LUMINOSITY FUNCTIONS AT REDSHIFTS<i>z</i>∼ 4 TO<i>z</i>∼ 10: 10,000 GALAXIES FROM<i>HST</i>LEGACY FIELDS

The remarkable Hubble Space Telescope(HST) data sets from the CANDELS, HUDF09, HUDF12, ERS, and BoRG/HIPPIES programs have allowed us to map the evolution of the rest-frame UV luminosity function (LF) from z 10 to z 4. We develop new color criteria that more optimally utilize the full wavelength coverage from the optical, near-IR, and mid-IR observations over our search fields, while simultaneously minimizing the incompleteness and eliminating redshift gaps. We have identified 5859, 3001, 857, 481, 217, and 6 galaxy candidates at z 4, z 5, z 6, z 7, z 8, and z 10, respectively, from the 1000 arcmin 2 area covered by these data sets. This sample of >10,000 galaxy candidates at z 4 is by far the largest assembled to date with HST. The selection of z 4-8 candidates over the five CANDELS fields allows us to assess the cosmic variance; the largest variations are at z 7. 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* galaxies and allow us to reassess the form of the UV LFs. Our new LF results strengthen our earlier findings to s 3.4 significance for a steeper faint-end slope of the UV LF at > z 4, with evolving from a = - 1.64 0.04 at z 4 to a = - 2.06 0.13 at z 7 (and a = - 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 f*. 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 + - z ( (