Tides, Interactions, and Fine-Scale Substructures in Galaxy Clusters

We present the results of a study on galaxy interactions, tides, and otherprocesses which produce luminous fine-scale substructures in the galaxyclusters: Coma, Perseus, Abell 2199, AWM 3 and AWM 5. All unusual structures inthese clusters can be categorized in seven morphologies: interacting galaxies,multiple galaxies (non-interacting), distorted galaxies, tailed galaxies, linegalaxies, dwarf galaxy groups and galaxy aggregates. The various morphologiesare described, and a catalog is presented of 248 objects in these five clustersalong with color, and positional information obtained from CCD images takenwith the WIYN 3.5m telescope in broadband B and R filters. Distorted, interacting, and fine-scale substructures have a range of colorsextending from blue objects with B-R $\approx$ 0, to redder colors at B-R$\approx$ 2.5. We also find that the structures with the most disturbedmorphology have the bluest colors. Additionally, the relative numberdistributions of these structures suggests that two separate classes of galaxyclusters exist: one dominated by distorted structures and the other dominatedby galaxy associations. The Coma and Perseus clusters, respectively, areproposed as models for these types of clusters. Possible mechanisms for the production of fine-scale substructure arereviewed and compared to observations of z $\approx$ 0.4 Butcher-Oemlerclusters. We conclude, based on color, positional, and statistical data, thatthe most likely mechanism for the creation of these structures is through aninteraction with the gravitational potential of the cluster, possibly coupledwith effects of high speed interactions with large cluster ellipticals.Comment: To appear in January AJ, 47 Page Manuscript with 21 Figure