HST EMISSION LINE GALAXIES at z ∼ 2: COMPARING PHYSICAL PROPERTIES of LYMAN ALPHA and OPTICAL EMISSION LINE SELECTED GALAXIES

We compare the physical and morphological properties of z ∼ 2 Lyα emitting galaxies (LAEs) identified in the HETDEX Pilot Survey and narrow band studies with those of z ∼ 2 optical emission line selected galaxies (oELGs) identified via HST WFC3 infrared grism spectroscopy. Both sets of galaxies extend over the same range in stellar mass (7.5 < logM/M⊙ < 10.5), size (0.5 < R < 3.0 kpc), and star formation rate (∼1 < SFR < 100 M⊙ yr^?1). Remarkably, a comparison of the most commonly used physical and morphological parameters - stellar mass, half-light radius, UV slope, SFR, ellipticity, nearest neighbor distance, star formation surface density, specific SFR, [O iii] luminosity, and [O iii] equivalent width - reveals no statistically significant differences between the populations. This suggests that the processes and conditions which regulate the escape of Lyα from a z ∼ 2 star-forming galaxy do not depend on these quantities. In particular, the lack of dependence on the UV slope suggests that Lyα emission is not being significantly modulated by diffuse dust in the interstellar medium. We develop a simple model of Lyα emission that connects LAEs to all high-redshift star-forming galaxies where the escape of Lyα depends on the sightline through the galaxy. Using this model, we find that mean solid angle for Lyα escape is steradians; this value is consistent with those calculated from other studies.