The Lyman alpha reference sample: IV. Morphology at low and high redshift

The transport of Ly alpha photons in galaxies is a complex process and the conditions under which Ly alpha photons manage to escape from certain galaxies is still under investigation. The Lyman alpha reference sample (LARS) is a sample of 14 local starforming galaxies, designed to study Ly alpha in detail and relate it to restframe UV and optical emission. With the aim of identifying restframe UV and optical properties, which are typical of Ly alpha emitters at both low and high redshift, we investigated the morphological properties of the LARS galaxies, in particular the ones that exhibit intense Ly alpha radiation. We measured sizes and morphological parameters in the continuum, Ly alpha , and H alpha images. We studied morphology by using the Gini coefficient vs. M20 and asymmetry vs. concentration diagrams. The stack of LARSLAE Ly alpha images is peaked in the centre, indicating that the conditions, which make a galaxy an LAE, tend to produce a concentrated surface brightness profile. On the other hand, the stack of all LARS galaxies is shallower and more extended.