Lyman alpha emitters are a type of distant galaxy

Galaxy

A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...

 that emits Lyman-alpha

Lyman series

In physics and chemistry, the Lyman series is the series of transitions and resulting ultraviolet emission lines of the hydrogen atom as an electron goes from n ≥ 2 to n = 1...

 radiation. They are extremely distant and because of the finite travel time of light they are glimpses of the past history of the universe. They are thought to be the progenitors of most modern Milky Way

Milky Way

The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...

 type galaxies. These galaxies can be found nowadays rather easily in narrow-band searches by an excess of their narrow-band flux at a wavelength which may be interpreted as their redshift

Redshift

In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...

:
where z is the redshift, is the observed wavelength, and 1215.67 Å is the wavelength of Lyman-alpha emission. The Lyman-alpha line is thought to be caused by an ongoing outburst of star-formation. Experimental observations of the redshift of LAEs are important in cosmology

Cosmology

Cosmology is the discipline that deals with the nature of the Universe as a whole. Cosmologists seek to understand the origin, evolution, structure, and ultimate fate of the Universe at large, as well as the natural laws that keep it in order...

 because they trace dark matter

Dark matter

In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...

 halos and subsequently the evolution of matter distribution in the universe.

See also

• Lyman series
  Lyman series
  In physics and chemistry, the Lyman series is the series of transitions and resulting ultraviolet emission lines of the hydrogen atom as an electron goes from n ≥ 2 to n = 1...
  
  
• Lyman alpha blob
• Lyman-break galaxy
  Lyman-break galaxy
  Lyman-break galaxies are star-forming galaxies at high redshift that are selected using the differing appearance of the galaxy in several imaging filters due to the position of the Lyman limit...
  
  
• Damped Lyman-alpha system
• Lyman-alpha forest
  Lyman-alpha forest
  In astronomical spectroscopy, the Lyman-alpha forest is the sum of absorption lines arising from the Lyman-alpha transition of the neutral hydrogen in the spectra of distant galaxies and quasars....
  
  
• Lyman limit
  Lyman limit
  The Lyman limit is the short-wavelength end of the Hydrogen Lyman series, at 91.2 nm. It corresponds to the energy required for an electron in the Hydrogen ground state to escape from the electric potential barrier that originally confined it, thus creating a Hydrogen ion...