We present a structural and photometric analysis of 42 elliptical/lenticular galaxies in ( E/S0 + S ) pairs observed in the BVRI color bands .
The aim of the analysis is to empirically determine the effects of interactions on their morphology , structure and stellar populations as seen from the light concentration ( C ) , asymmetry ( A ) , and clumpiness ( S ) parameters .
We further compare these values to a control sample of 67 mostly isolated non-interacting E/S0 galaxies .
We find that the paired E/S0 galaxies occupy a more scattered loci in CAS space than non-interacting E/S0 ’ s , and that the effects of interactions on E/S0 ’ s are minor , in contrast to disk galaxies involved in interactions .
This suggests that observational methods for recognizing interactions at high redshift , such the CAS methodology of Conselice ( 2003 ) , would hardly detect E/S0 ’ s involved in interactions ( related to early phases of the so called ‘ dry-mergers ’ ) , and that the majority of interacting galaxies identified at high redshift must be gas dominated systems .
We however find statistical differences in the asymmetry index when comparing isolated and interacting E/S0s .
In the mean , paired E/S0 galaxies have A values 2.96 \pm 0.72 times larger than the ones of non-interacting E/S0 ’ s .
For the subset of presumably strongly interacting E/S0 ’ s , A and S can be several times larger than the typical values of the isolated E/S0 ’ s .
We show that the asymmetries are consistent with several internal and external morphological distortions .
We conclude that the subset of interacting E/S0s should be dense , gas poor galaxies in systems spaning a wide range of interaction stages , with typical merging timescales { { } _ { > } \atop { { } ^ { \sim } } } 0.1 - 0.5 Gyr .
We use the observed phenomenology of this subsample to predict the approximate loci of ‘ dry pre-mergers ’ in the CAS parameter space .