Astrophysics (Index)About

luminous infrared galaxy

(a galaxy emitting a lot of far-infrared light)

A luminous infrared galaxy (LIRG) is a galaxy emitting more than 1011 times solar luminosity in the far infrared.

They are often a starburst galaxy and/or have an active galactic nucleus or a quasar. The relatively high infrared stems from dust heated by the electromagnetic radiation (EMR) of the AGN or star formation (SF), re-emitting the EMR in a cooler (infrared-intensive) black body spectrum, that can exceed the directly-viewed emission from the star formation or AGN. Generally, the higher the IR, the higher the star formation rate (SFR). LIRGs are among the brightest objects in the universe. Variations:

(Sources also cite these thresholds as applying to the galaxy's full bolometric luminosity, sometimes stipulating that most of its emission is within the infrared or far infrared; I presume this is the typical case for such bright galaxies.)

A LIRG is essentially the same as a submillimeter galaxy (SMG).

(galaxy type,infrared)
Further reading:

Referenced by pages:
hyperluminous infrared galaxy (HLIRG)
submillimeter galaxy (SMG)
ultraluminous infrared galaxy (ULIRG)