Lyman-alpha emitter

A Lyman-alpha emitter (LAE) is a type of astronomical object, typically a galaxy, that exhibits strong emission of Lyman-alpha radiation. The Lyman-alpha line corresponds to a specific wavelength of ultraviolet light (121.6 nanometers) emitted by hydrogen atoms when an electron transitions from the second lowest energy level (n=2) to the ground state (n=1). Lyman-alpha emitters are of particular interest in studies of the early universe.