HUBBLE SPACE TELESCOPE IMAGING OF Ly alpha EMISSION AT z approximate to 4.4

We present the highest redshift detections of resolved Ly alpha emission, using Hubble Space Telescope (HST)/Advanced Camera for Surveys F658N narrowband-imaging data taken in parallel with the Wide Field Camera 3 Early Release Science program in the GOODS Chandra Deep Field-South. We detect Ly alpha emission from three spectroscopically confirmed z = 4.4 Ly alpha emitting galaxies (LAEs), more than doubling the sample of LAEs with resolved Ly alpha emission. Comparing the light distribution between the rest-frame ultraviolet continuum and narrowband images, we investigate the escape of Ly alpha photons at high redshift. While our data do not support a positional offset between the Ly alpha and rest-frame ultraviolet (UV) continuum emission, the half-light radius in one out of the three galaxies is significantly (> 1 sigma) larger in Ly alpha than in the rest-frame UV continuum. Stacking the three LAEs in both the narrowband and UV continuum images, we find that the Ly alpha light appears larger than the rest-frame UV at 4.2 sigma significance. This Ly alpha flux detected with HST is a factor of 4-10 less than observed in similar filters from the ground. These results together imply that the Ly alpha emission is not strictly confined to its indigenous star-forming regions. Rather, for at least one object the Ly alpha emission is more extended, with the missing HST flux possibly existing in a diffuse outer halo. This suggests that the radiative transfer of Ly alpha photons in high-redshift LAEs is complicated, with the interstellar-medium geometry and/or outflows playing a significant role in galaxies at these redshifts.