2001ApJ...560L.119E

We discuss the physical nature of a remarkably faint pair of Lyα-emitting images discovered close to the giant cD galaxy in the lensing cluster Abell 2218 (z=0.18) during a systematic survey for highly magnified star-forming galaxies beyond z=5. A well-constrained mass model suggests the pair arises via a gravitationally lensed source viewed at high magnification. Keck spectroscopy confirms the lensing hypothesis and implies that the unlensed source is a very faint (I∼30), compact (<150 h^–1₆₅ pc), and isolated object at z=5.576 whose optical emission is substantially contained within the Lyα emission line; no stellar continuum is detectable. The available data suggest the source is a promising candidate for an isolated ∼10⁶ M_☉ system seen producing its first generation of stars close to the epoch of reionization.