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We present new results on the spectrally resolved Lyman-alpha (LyA) emissionof three LyA emitting field galaxies at z~2.4 with high LyA equivalent width(>100 Angstroms) and LyA luminosity (~10^43 erg/s). At 120 km/s (FWHM) spectralresolution, the prominent double-peaked LyA profile straddles the systemicvelocity, where the velocity zero-point is determined from spectroscopy of thegalaxies' rest-frame optical nebular emission lines. The average velocityoffset from systemic of the stronger redshifted emission component for oursample is 176 km/s while the average total separation between the redshiftedand main blueshifted emission components is 380 km/s. These measurements are afactor of ~2 smaller than for UV continuum-selected galaxies that show LyA inemission with lower LyA equivalent width. We compare our LyA spectra to thepredicted line profiles of a spherical "expanding shell" LyA radiative transfergrid that models large-scale galaxy outflows. Specifically blueward of thesystemic velocity where two galaxies show a weak, highly blueshifted (by ~1000km/s) tertiary emission peak, the model line profiles are a relatively poorrepresentation of the observed spectra. Since the neutral gas column densityhas a dominant influence over the shape of the LyA line profile, we cautionagainst equating the observed LyA velocity offset with a physical outflowvelocity, especially at lower spectral resolution where the unresolved LyAvelocity offset is a convoluted function of several degenerate parameters.Referring to rest-frame ultraviolet and optical Hubble Space Telescope imaging,we find that galaxy-galaxy interactions may play an important role in inducinga starburst that results in copious LyA emission, as well as perturbing the gasdistribution and velocity field which have strong influence over the LyAemission line profile.

The Spectrally Resolved Lyman-alpha Emission of Three Lyman-alpha Selected Field Galaxies at z~2.4 from the HETDEX Pilot Survey