Physical Properties of Spectroscopically-Confirmed Galaxies at z >= 6. II. Morphology of the Rest-Frame UV Continuum and Lyman-alpha Emission

We present a detailed structural and morphological study of a large sample of spectroscopically-confirmed galaxies at z >= 6, using deep HST near-IR broad-band images and Subaru optical narrow-band images. The galaxy sample consists of 51 Lyman-alpha emitters (LAEs) at z ~ 5.7, 6.5, and 7.0, and 16 Lyman-break galaxies (LBGs) at 5.9 = 6 in previous studies. In addition, more luminous galaxies tend to have larger sizes, exhibiting a weak size-luminosity relation r_{hl,in} \propto L^{0.14} at M_1500 = 6 galaxies with nonparametric methods, including the CAS system and the Gini and M_20 parameters, and demonstrate their validity through simulations. We search for extended Lyman-alpha emission halos around LAEs at z ~ 5.7 and 6.5, by stacking a number of narrow-band images. We do not find evidence of extended halos predicted by cosmological simulations. Such Lyman-alpha halos, if they exist, could be weaker than predicted. Finally, we investigate any positional misalignment between UV continuum and Lyman-alpha emission in LAEs. While the two positions are generally consistent, several merging galaxies show significant positional differences. This is likely caused by a disturbed ISM distribution due to merging activity.