2019ApJ...884....7E

Low-mass, low-metallicity galaxies at low to moderate (z <= 3) redshifts offer the best opportunity for detailed examination of the interplay between massive stars, ionizing radiation and gas in sources similar to those that likely reionized the universe. We present new narrowband Hubble Space Telescope observations of Lyαemission and the adjacent ultraviolet (UV) continuum in the low-mass (M_* = 2 x 10⁸ M_☉), low-metallicity (Z ∼ 1/20 Z_☉), and highly ionized gravitationally lensed galaxy SL2S J02176-0513 at z = 1.844. The galaxy has strong Lyαemission with photometric equivalent width W_Lyα^phot=218±12Å, at odds with the Lyαescape fraction of 10%. However, the spectroscopic Lyαprofile suggests the presence of broad absorption underlying the emission, and the total equivalent width is consistent with the escape fraction once this underlying absorption is included. The Lyαemission is more spatially extended than the UV continuum, and the 0.''14 spatial resolution of HST coupled with the magnification of gravitational lensing enables us to examine the distribution of Lyαand the UV continuum on subkiloparsec scales. We find that the peaks of the Lyαemission and the UV continuum are offset by 650 pc, and there is no Lyαemission arising from the region with the strongest UV light. Our combined spectroscopic and imaging data imply a significant range in neutral hydrogen column density across the object. These observations offer indirect support for a model in which ionizing radiation escapes from galaxies through channels with low column density of neutral gas.