Publication Date

2010

Abstract

We present the highest redshift detections of resolved Ly emission, using Hubble Space Telescope/ACS F658N narrowband-imaging data taken in parallel with the Wide Field Camera 3 Early Release Science program in the GOODS CDF-S. We detect Ly emission from three spectroscopically confirmed z = 4.4 Ly emitting galaxies (LAEs), more than doubling the sample of LAEs with resolved Ly emission. Comparing the light distribution between the rest-frame ultraviolet continuum and narrowband images, we investigate the escape of Ly photons at high redshift. While our data do not support a positional offset between the Ly and rest-frame ultraviolet (UV) continuum emission, the half-light radii in two out of the three galaxies are significantly larger in Ly than in the rest-frame UV continuum. This result is confirmed when comparing object sizes in a stack of all objects in both bands. Additionally, the narrowband flux detected with HST is significantly less than observed in similar filters from the ground. These results together imply that the Ly emission is not strictly confined to its indigenous star-forming regions. Rather, the Ly emission is more extended, with the missing HST flux likely existing in a diffuse outer halo. This suggests that the radiative transfer of Ly photons in high-redshift LAEs is complicated, with the interstellar-medium geometry and/or outflows playing a significant role in galaxies at these redshifts.

Comments

This is the pre-published version harvested from ArXiv.

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