A luminous infrared galaxy
), is a galactic body
whose defining characteristic is in emitting more than 1011
solar luminosities in the far-infrared
part of the electromagnetic spectrum. A more luminous system, emitting more than 1012 solar luminosities
in the far-infrared, is called ultraluminous infrared galaxy
). An even more luminous system, emitting more than 1013
solar luminosities in the far-infrared, is called hyperluminous infrared galaxy
). Most LIRGs and ULIRGs emit at least 90% of their light in the infrared
Most LIRGs and all ULIRGs show signs of recent or continuing interactions and disruptions. Many are starburst galaxies, and some also contain an active galactic nucleus. ULIRGs are implicated in a variety of interesting astrophysical phenomena including the formation of quasars and elliptical galaxies. Local examples of ULIRGs are often used as analogs of galaxy formation at high redshift. ULIRGs seem to be embedded in dark matter halo with masses of around 10 trillion solar masses.
- II Zw 96 a luminous infrared galaxy containing young powerful starburst regions.
- NGC 6240 a luminous infrared galaxy with two nuclei.