Galaxy Formation and Reionization: Key Unknowns and Expected
  Breakthroughs by the James Webb Space Telescope
  The scheduled launch of James Webb Space Telescope (JWST) in late 2021 marks
a new start for studies of galaxy formation at high redshift z>~6 during the
era of Cosmic Reionization. JWST can capture sensitive, high-resolution images
and multi-object spectroscopy in the infrared that will transform our view of
galaxy formation during the first billion years of cosmic history. This review
summarizes our current knowledge of the role of galaxies in reionizing
intergalactic hydrogen ahead of JWST, achieved through observations with Hubble
Space Telescope and ground-based facilities including Keck, the Very Large
Telescope, Subaru, and the Atacama Large Millimeter/Submillimeter Array. We
identify outstanding questions in the field that JWST can address during its
mission lifetime, including with the planned JWST Cycle 1 programs. (Abridged)
