The Role of Preprocessing in Tidal Feature Formation within Galaxy Clusters

We investigate the formation of tidal features, such as tidal tails, streams, and shell-like structures, composed of stars stripped from satellites within galaxy clusters. For this, we use multiresolution cosmological N-body simulations with the “galaxy replacement technique.” We find that the fraction of satellites with tidal features increases with the mass of the host cluster but is not related to the dynamical state of the cluster. Although the strong tidal field in the cluster environment accelerates mass loss of the satellites, only 20% of tidal-featured galaxies form their tidal features purely due to tidal perturbations in the cluster environment, without any interactions with other galaxies before falling into the cluster. In contrast, the majority (80%) are affected by preprocessing, as they experienced merger events with other galaxies before falling into the cluster. Among this preprocessing population, 45% of all tidal-featured galaxies form their tidal features after passing the pericenter of the cluster, and are affected by both preprocessing and the tidal field of the cluster, whereas 35% of all tidal-featured galaxies form their tidal features before reaching the pericenter, primarily due to preprocessing. Notably, this fraction increases from 35% to 40%–50% when we focus only on galaxies with brighter surface brightness limits or higher stellar masses. Therefore, our results highlight that preprocessing is an important channel for forming tidal features within clusters. However, the importance of preprocessing may be further amplified in observations, since more massive galaxies, which are commonly associated with preprocessing, are preferentially detected.