Observational Searches for Galaxies at z > 6
  Although the universe at redshifts greater than six represents only the first
one billion years (<10%) of cosmic time, the dense nature of the early universe
led to vigorous galaxy formation and evolution activity which we are only now
starting to piece together. Technological improvements have, over only the past
decade, allowed large samples of galaxies at such high redshifts to be
collected, providing a glimpse into the epoch of formation of the first stars
and galaxies. A wide variety of observational techniques have led to the
discovery of thousands of galaxy candidates at z > 6, with spectroscopically
confirmed galaxies out to nearly z = 9. Using these large samples, we have
begun to gain a physical insight into the processes inherent in galaxy
evolution at early times. In this review, I will discuss i) the selection
techniques for finding distant galaxies, including a summary of previous and
ongoing ground and space-based searches, and spectroscopic followup efforts,
ii) insights into galaxy evolution gleaned from measures such as the rest-frame
ultraviolet luminosity function, the stellar mass function, and galaxy
star-formation rates, and iii) the effect of galaxies on their surrounding
environment, including the chemical enrichment of the universe, and the
reionization of the intergalactic medium. Finally, I conclude with prospects
for future observational study of the distant universe, using a bevy of new
state-of-the-art facilities coming online over the next decade and beyond.
