Editing Galaxy (section)

=== Luminous infrared galaxy ===
{{Main|Luminous infrared galaxy}}

Luminous infrared galaxies (LIRGs) are galaxies with luminosities—the measurement of electromagnetic power output—above 10<sup>11</sup> L☉ (solar luminosities). In most cases, most of their energy comes from large numbers of young stars which heat surrounding dust, which reradiates the energy in the infrared.  Luminosity high enough to be a LIRG requires a star formation rate of at least 18&nbsp;M☉&nbsp;yr<sup>−1</sup>. Ultra-luminous infrared galaxies (ULIRGs) are at least ten times more luminous still and form stars at rates >180&nbsp;M☉&nbsp;yr<sup>−1</sup>.  Many LIRGs also emit radiation from an AGN.<ref>{{Cite journal |last1=Pérez-Torres |first1=Miguel |last2=Mattila |first2=Seppo |last3=Alonso-Herrero |first3=Almudena |last4=Aalto |first4=Susanne |last5=Efstathiou |first5=Andreas |date=December 2021 |title=Star formation and nuclear activity in luminous infrared galaxies: an infrared through radio review |url=https://link.springer.com/10.1007/s00159-020-00128-x |journal=[[The Astronomy and Astrophysics Review]] |language=en |volume=29 |issue=1 |page=2 |arxiv=2010.05072 |bibcode=2021A&ARv..29....2P |doi=10.1007/s00159-020-00128-x |s2cid=253687419 |issn=0935-4956}}</ref><ref name=":0">{{Cite journal |last1=Bellocchi |first1=E. |last2=Pereira-Santaella |first2=M. |last3=Colina |first3=L. |last4=Labiano |first4=A. |last5=Sánchez-García |first5=M. |last6=Alonso-Herrero |first6=A. |last7=Arribas |first7=S. |last8=García-Burillo |first8=S. |last9=Villar-Martín |first9=M. |last10=Rigopoulou |first10=D. |last11=Valentino |first11=F. |last12=Puglisi |first12=A. |last13=Díaz-Santos |first13=T. |last14=Cazzoli |first14=S. |last15=Usero |first15=A. |date=August 2022 |title=Compact molecular gas emission in local LIRGs among low- and high- z galaxies |url=https://www.aanda.org/10.1051/0004-6361/202142802 |journal=[[Astronomy & Astrophysics]] |volume=664 |pages=A60 |doi=10.1051/0004-6361/202142802 |issn=0004-6361|arxiv=2204.02055 |bibcode=2022A&A...664A..60B }}</ref> Infrared galaxies emit more energy in the infrared than all other wavelengths combined, with peak emission typically at wavelengths of 60 to 100 microns. LIRGs are believed to be created from the strong interaction and merger of   spiral galaxies.<ref>{{Cite journal |last1=Sanders |first1=David B. |last2=Mirabel |first2=I. F. |date=Sep 1996 |title=Luminous Infrared Galaxies |url=https://ned.ipac.caltech.edu/level5/Sanders/paper.pdf |journal=[[Annual Review of Astronomy and Astrophysics]] |language=en |volume=34 |issue=1 |pages=749–792 [772–773] |doi=10.1146/annurev.astro.34.1.749 |bibcode=1996ARA&A..34..749S|issn=0066-4146}}</ref> While uncommon in the local universe, LIRGs and ULIRGS were more prevalent when the universe was younger.<ref name=":0" />