Key points are not available for this paper at this time.
A largely complete sample of 20 close pairs of faint (B <= 22) galaxies, separated by less than 4. 5", is selected from catalogs based on UBVI photometry of 4 m plates taken in two regions of high galactic latitude (SA 57 and SA 68) which cover a total area of 0. 5 deg²^. The colors of the galaxy pairs indicate recently enhanced star formation in some systems, but generally the distribution of the colors and size of the galaxies in pairs is not significantly different from that of equally faint field galaxies. The number of pairs is roughly similar to the number expected from an extrapolation to small scales of the angular correlation function of the entire sample of faint galaxies, but there is some evidence, significant at about the 90% level, for an overabundance of pairs of galaxies separated by about 3. 0". This rough agreement between the observed number of galaxy pairs and the extrapolation of the angular correlation function to separations as small as typical galactic radii is similar to that found in comparable studies of much brighter samples. A comparison of the number of close galaxy pairs in our faint sample to the number found in comparable nearby studies suggests that the frequency of interacting galaxies increases as (1 + z) ⁴. 0 +/- 2. 5^. This result lends observational support to the hypothesis that interactions were more common in the past than they are now, but its dependence on the assumption that the faint galaxy pairs are moderate-redshift analogs of nearby pairs with a distribution of absolute magnitudes not very different from equally faint field galaxies makes this conclusion tentative until further observations become available.
Zepf et al. (Wed,) studied this question.