A Correlation Between Ly{α} Spectral Line Profile and Rest-Frame UV Morphology

We explore the relationship between the spectral shape of the Ly{\alpha} emission and the UV morphology of the host galaxy using a sample of 304 Ly{\alpha}-emitting BV i-dropouts at 3 < z < 7 in the GOODS and COSMOS fields. Using our extensive reservoir of high-quality Keck DEIMOS spectra combined with HST WFC3 data, we measure the Ly{\alpha} line asymmetries for individual galaxies and compare them to axial ratios measured from observed J- and H-band (restframe UV) images. We find that the Ly{\alpha} skewness exhibits a large scatter at small elongation (a/b < 2), and this scatter decreases as axial ratio increases. Comparison of this trend to radiative transfer models and various results from literature suggests that these high-redshift Ly{\alpha} emitters are not likely to be intrinsically round and symmetric disks, but they probably host galactic outflows traced by Ly{\alpha} emitting clouds. The ionizing sources are centrally located, with the optical depth a good indicator of the absorption and scattering events on the escape path of Ly{\alpha} photons from the source. Our results find no evidence for evolution in Ly{\alpha} asymmetry or axial ratio with look-back time.