Luminous Infrared Galaxies in the Local Universe

We study the morphology and star formation properties of 159 local luminousinfrared galaxy (LIRG) using multi-color images from Data Release 2 (DR2) ofthe Sloan Digital Sky Survey (SDSS). The LIRGs are selected from across-correlation analysis between the IRAS survey and SDSS. They are allbrighter than 15.9 mag in the r-band and below redshift ~ 0.1, and so can bereliably classified morphologically. We find that the fractions ofinteracting/merging and spiral galaxies are ~ 48% and ~ 40% respectively. Ourresults complement and confirm the decline (increase) in the fraction of spiral(interacting/merging) galaxies from z ~1 to z ~ 0.1, as found by Melbourne, Koo& Le Floc'h (2005). About 75% of spiral galaxies in the local LIRGs are barred,indicating that bars may play an important role in triggering star formationrates > 20 M_{sun}/yr in the local universe. Compared with high redshift LIRGs,local LIRGs have lower specific star formation rates, smaller cold gasfractions and a narrower range of stellar masses. Local LIRGs appear to beeither merging galaxies forming intermediate mass ellipticals or spiralgalaxies undergoing high star formation activities regulated by bars.Comment: 22 pages, 5 figures, accepted for publication in ApJ, title changed, typos corrected,major revisions following referee's comments,updated reference