THE UV-CONTINUUM PROPERTIES OF Lyα-SELECTED GALAXIES AT z=6.5

We report the first space-based very deep near-infrared continuum observations of a uniform sample of z = 6.5 galaxies with log(L(Ly alpha)) = 42.5-43 erg s(-1) selected from narrowband line searches and with spectroscopically confirmed Ly alpha emission. The 1.4 mu m Hubble Space Telescope WFC3 observations are deep enough (AB(1 sigma) = 28.75) to measure individual continuum magnitudes at this redshift for all of the objects. We compare the results with continuum-selected samples at the same redshift and find that Ly alpha emission is present in 24% of all galaxies with M-AB(1350 angstrom) < -20 at z = 6.5. The error in this quantity is dominated by systematic uncertainties, which could be as large as multiplicative factors of three. The Ly alpha galaxies are extended but small (size < 1 kpc), and have star formation rates of approximately 10 M-circle dot yr(-1). We find a mean L(Ly alpha)/nu L-nu at 1400 angstrom to be 0.08, with the seven objects showing a range from 0.026 to 0.26, implying that there is little sign of destruction of the Ly alpha line. All of the properties of the z = 6.5 sample appear to be very similar to those of Ly alpha emitters at lower redshifts.