We present a deep broadband optical imaging study of a complete sample of luminous elliptical galaxies ( M _ { B } < -20 ) at distances 15 Mpc - 50 Mpc , selected from the Tully catalog of nearby galaxies .
The images are flat to \sim 0.35 % across the 20 ’ field and reach a V band depth of 27.7 mag arcsec ^ { -2 } .
We derive an objective tidal interaction parameter for all galaxies and find that 73 % of them show tidal disturbance signatures in their stellar bodies .
This is the first time that such an analysis is done on a statistically complete sample and it confirms that tidal features in ellipticals are common even in the local Universe .
From the dynamical time of the sample galaxies at the innermost radius where tidal features are detected we estimate the mass assembly rate of nearby ellipticals to be dM / M \sim 0.2 per Gyr with large uncertainty .
We explore the relation between gravitational interaction signatures and the galaxy environment and find that galaxies in clusters are less disturbed than group and field galaxies .
We also study how these interactions affect the broadband colors of ellipticals and find a moderate correlation , suggesting that the mergers are not accompanied by significant star-formation .
Lastly , we find no correlation between AGN activity , as measured by 6cm radio emission , and large scale tidal distortions .
This implies that gravitational interactions are not the only , and perhaps not the most important , trigger of nuclear activity .
In summary , we find that elliptical galaxies in groups and low density environments continue to grow at the present day through mostly “ dry ” mergers involving little star formation .