Effects of interactions on galaxy properties in the main galaxy sample of SDSS data release 5

From the main galaxy sample of the Sloan Digital Sky Survey Data Release 5, we construct samples of paired and isolated galaxies to investigate the effects of interactions on galaxy properties. To account for the radial selection effect in the main galaxy sample, we divide the whole redshift region into 18 bins of width Delta z = 0.01 and perform a comparative study of statistical properties between paired and isolated galaxies in each redshift bin. We find that the early- type fraction of paired galaxies is far higher than that of isolated galaxies, which supports the hypothesis that interactions are the major morphological driver. We also explore the dependence of paired galaxies' properties on the three- dimensional separation between pair members and find an obvious trend inwhich the early- type fraction of paired galaxies depends on the separation: closer pairs have a higher early- type fraction. This could result from the higher proportion of interactions and mergers in close pairs than in pairs with greater three- dimensional separation.