The First Half Billion Years: Results from the Frontier Fields

The Frontier Fields program is transforming our understanding of galaxy evolution in the first 550 million years (z > 9). Where previous programs yielded perhaps a dozen z > 9 candidates, we estimate the Frontier Fields may yield up to ~70 (~6 per field). The first Frontier Fields images yielded strong z ~ 8 and 9 candidates, but fewer than expected at z > 9 (including one triply-imaged z ~ 10 candidate). By the time of this meeting, Hubble and Spitzer will have completed deep Frontier Fields imaging of the first four pairs of new "blank" fields and nearby fields strongly lensed by galaxy clusters. In this talk, I will present our latest high-redshift candidates, constraints on high-redshift luminosity functions, and implications for reionization. I will discuss whether the deficit of faint z > 9 galaxies persists (as also found in the UDF) and how incompleteness may be affecting our results.