Resolving Clumpy versus Extended Ly in Strongly Lensed, High-redshift Ly Emitters

We present six strongly gravitationally lensed Ly alpha emitters (LAEs) at z similar to 4-5 with Hubble Space Telescope (HST) narrowband imaging isolating Ly alpha. Through complex radiative transfer Ly alpha encodes information about the spatial distribution and kinematics of the neutral hydrogen upon which it scatters. We investigate the galaxy properties and Ly alpha morphologies of our sample. Many previous studies of high-redshift LAEs have been limited in Ly alpha spatial resolution. In this work we take advantage of high-resolution Ly alpha imaging boosted by lensing magnification, allowing us to probe subgalactic scales that are otherwise inaccessible at these redshifts. We use broadband imaging from HST (rest-frame UV) and Spitzer (rest-frame optical) in spectral energy distribution fitting, providing estimates of the stellar masses (similar to 10(8)-10(9)M(circle dot)), stellar population ages (t(50) < 40 Myr), and amounts of dust (A(V) similar to 0.1-0.6, statistically consistent with zero). We employ nonparametric star formation histories to probe the young stellar populations which create the Ly alpha. We also examine the offsets between the Ly alpha and stellar continuum, finding small upper limits of offsets (<0.'' 1) consistent with studies of low-redshift LAEs, indicating our galaxies are not interacting or merging. Finally, we find a bimodality in our sample's Ly alpha morphologies: clumpy and extended. We find a suggestive trend: our LAEs with clumpy Ly alpha are generally younger than the LAEs with extended Ly alpha, suggesting a possible correlation with age.