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摘要
We combine a large, homogeneous sample of similar to 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-circle dot (which translates to a median star formation rate of around 15 M-circle dot 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-circle dot yr(-1)) and producing systems that are classified as luminous infrared galaxies (LIRGS; 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 similar to 160 Myr.
- 出版日期2015-5
