We combine a large , homogeneous sample of \sim 3000 local mergers with the Imperial IRAS Faint Source Redshift Catalogue ( IIFSCz ) , to perform a blind far-infrared ( FIR ) study of the local merger population .
The IRAS-detected mergers are mostly ( 98 \% ) spiral-spiral systems , residing in low density environments , a median FIR luminosity of 10 ^ { 11 } L _ { \odot } ( which translates to a median star formation rate of around 15 M _ { \odot } yr ^ { -1 } ) .
The FIR luminosity – and therefore the star formation rate – shows little correlation with group richness and scales with the total stellar mass of the system , with little or no dependence on the merger mass ratio .
In particular , minor mergers ( mass ratios < 1 : 3 ) are capable of driving strong star formation ( between 10 and 173 M _ { \odot } yr ^ { -1 } ) and producing systems that are classified as LIRGs , luminous infrared galaxies ( 65 \% of our LIRGs are minor mergers ) , with some minor-merging systems being close to the ultra luminous infrared galaxy ( ULIRG ) limit .
Optical emission line ratios indicate that the AGN fraction increases with increasing FIR luminosity , with all ULIRG mergers having some form of AGN activity .
Finally , we estimate that the LIRG-to-ULIRG transition along a merger sequence typically takes place over a relatively short timescale of \sim 160 Myr .