Pushing Back Studies of Galaxies Toward the Dark Ages: High-Redshift Lyman alpha Emission-Line Galaxies in the Field

Lyman alpha emission presents a means of identifying very high redshift galaxies, provided such objects can be reliably distinguished from foreground emission-line galaxies. Here we report on a program of imaging and spectroscopic studies being conducted with the Keck telescope, in concert with additional efforts from the ground and with HST, to study such high-redshift objects over the range from z=3 to 7. The first deep narrow-band imaging studies with Keck are used to show that strong Lyman alpha emitters, such as have been seen in high-redshift quasar fields at z>4.5, can be found in the field populations. Based on studies of the HDF and the Hawaii Survey Fields these are significant contributors to the star formation rates at these epochs.