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

We present a detailed structural and morphological study of a large sample of spectroscopically confirmed galaxies at z >= 6 using deep Hubble Space Telescope (HST) near-IR broad-band images and Subaru Telescope optical narrow-band images. The galaxy sample consists of 51 Lyα emitters (LAEs) at z ~= 5.7, 6.5, and 7.0, and 16 Lyman break galaxies (LBGs) at 5.9 = 6 found in previous studies. In addition, more luminous galaxies tend to be larger and exhibit a weak size-luminosity relation, r hl, invpropL 0.14 at M 1500 = 6 galaxies with nonparametric methods, including the concentration, asymmetry, and smoothness system and the Gini and M 20 parameters, and demonstrate their validity through simulations. We search for extended Lyα 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 Lyα halos predicted by cosmological simulations. Such halos, if they exist, could be weaker than predicted. Finally, we investigate positional misalignment between the UV continuum and Lyα emissions in LAEs. While the two positions are generally consistent, several merging galaxies show significant positional differences. This is likely caused by a disturbed interstellar medium distribution due to merging activity. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Based in part on data collected at the Subaru Telescope and obtained from the Subaru-Mitaka-Okayama-Kiso Archive System (SMOKA), which is operated by the Astronomy Data Center, National Astronomical Observatory of Japan.