Astrophysics (Index)About

Lyman-break galaxy

(a galaxy emitting very little shorter than 912 angstroms)

A Lyman-break galaxy (LBG) is a galaxy identified as star forming by a lack of radiation emitted with wavelength shorter than 912 angstroms, the Lyman limit, i.e., the lower limit on wavelengths in the Lyman series. Neutral hydrogen around star-forming regions absorbs the radiation.

This method of identifying star-forming galaxies is largely used at redshifts of z in the 3-to-4 range, using filters on the redshifted spectrum. The method has the advantage that the "break" causes dropouts, i.e., images through some filters don't show the galaxy, providing a relatively easy way to identify them by comparing the filtered images, that the break is visible through the Earth's atmosphere within the 3-4 redshift range, and that the redshift can be determined with some precision using subsequent spectrography to identify the wavelength of the observed break.

(galaxy type)
Further reading:
LBGLBG J213512.73-010143general prefix for LBGs

Referenced by pages:
Balmer-break galaxy (BBG)
brightest cluster galaxy (BCG)