PUBLICATIONS OF THE ASTRONOMICAL OBSERVATORY OF BELGRADE104, Page 79-85, https://doi.org/10.69646/aob104p079
PROCEEDINGS of the XX Serbian Astronomical Conference, Belgrade, October 16 - 20, 2023, Edited by Jelena Petrović, Dušan Marčeta and Ana Lalović
Published by: Astronomical Observatory, Volgina 7, 11060 Belgrade 38, Serbia

Abstract. Galaxy flybys, a class of non-merger interactions, outnumber mergers at lower redshifts (e.g. z ≤ 2), particularly in higher-density environments. Some of the previous research adopted merger-based classification based on the mass ratio of interacting galaxies, differentiating between equal-mass and lower-mass flybys (i.e. major versus minor). However, cosmological simulations showed that major flybys are extremely rare and almost exclusively distant, while minor ones are much more frequent, with the secondary galaxy penetrating deep into the primary. We demonstrated that this leads to comparable strengths of interaction between the two sub-classes and essentially the same effects. Focusing on morphological consequences, we will showcase a few examples (formation of spirals, bars, and some complex structures). Thus, flybys should be classified primarily based on the interaction strength and explored further as they contribute to the structural diversity of galaxies observed in the local Universe.