Astro2020 Science White Paper: Synergies Between Galaxy Surveys and
  Reionization Measurements
  The early phases of galaxy formation constitute one of the most exciting
frontiers in astrophysics. It is during this era that the first luminous
sources reionize the intergalactic medium - the moment when structure formation
affects every baryon in the Universe. Here we argue that we will obtain a
complete picture of this era by combining observations of galaxies with direct
measurements of the reionization process: the former will provide a detailed
understanding of bright sources, while the latter will constrain the
(substantial) faint source population. We further describe how optimizing the
comparison of these two measurements requires near-infrared galaxy surveys
covering large volumes and retaining redshift information and also improvements
in 21-cm analysis, moving those experiments into the imaging regime.
