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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 the lack of radiation 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)
LBGLBG J213512.73-010143Lyman-Break Galaxygeneral prefix for LBGs

Referenced by:
Balmer-break Galaxy (BBG)
Brightest Cluster Galaxy (BCG)