A Lyman-Alpha Emitter (LAE or Lyman-Alpha Emitting Galaxy) is a Galaxy detected via the apparently-Redshifted (z) Lyman Alpha (Ly-α), the first Spectral Line of the Lyman Series. Given the confidence that the observed line is Lyman alpha, the redshift is:
λ 1 + z = ———————— 1215.67Å
The prominent Lyman-alpha line is assumed to be evidence of star formation. Surveys of such galaxies reveal the Star Formation (SF) history of the universe.