Gravitational interaction signatures in isolated galaxy triplet systems: A photometric analysis

Abstract Galaxy triplets are interesting laboratories where we can study the formation and the evolution of small and large systems of galaxies. This study aims to investigate signs of interaction between the members of nine isolated galaxy triplet systems (27 galaxies) selected from the “SDSS-based catalogue of Isolated Triplets” (SIT) with members brighter than 17.0 ( m r ≤ 17.0) in the r − band, and mean projected separation between the members of r p ≤ 0.1 Mpc. In this work, we performed a one-dimensional (1D) fitting of the surface brightness profiles and a two-dimensional (2D) modeling of the sample galaxies. In the 1D fitting, we examined the far outer part of the light profiles of disk galaxies (22 galaxies) and categorized them into type I (simple exponential), type II (down-bending), and type III (up-bending). This fitting results showed that 55 % of disk galaxies in our sample represent type III i.e are in state of interaction. In the 2D modeling, we fit smooth axisymmetric profiles to the 27 galaxies and found that 70 % exhibit asymmetric features and signs of interactions in their residual images. Thus, we conclude that galaxy triplets, with projected separations ( r p ≤ 0.1 Mpc) between their members, are physically bounded systems that show pronounced signs of interactions.