Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Astrophysics and Meteorology

Galaxy triplets represent one of the most interesting lab- oratory in identifying the formation and the evolution of galaxies. Understanding such systems will give us clues about the construction of larger groups and clusters of galaxies. In this thesis, we aim to investigate the nature of galaxy triplet systems and the possibility of merger be- tween their members. Toward that, we conduct a statis- tical study on 315 isolated triplet systems taken from the 2SDSS-based catalog of Isolated Triplets3(SIT) to obtain their physical and dynamical parameters. Meanwhile, the correlation between the dynamical parameters of these systems and the Large-Scale Structure (LSS) have been presented. Consequently, we confront our results with those obtained for a sample of triplets from the Local Su- percluster (LS), SDSS-triplets, Tully{u2019}s catalogue, Wide (W) and Compact (K) triplets. For further details about triplet systems and signs of interactions between their members, we applied surface photometry analysis and de- composition on nine galaxy triplets to declare their radial pro{uFB01}les and identify their {uFB01}ne structures. Interestingly, we found that triplet systems follow hierarchical structure in their formation and evolution. In addition, we found that signs of interactions are pronounced in systems with small projected separations between their members rp < 0.3 Mpc

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