The effect of cluster dynamical state on ram-pressure stripping

Abstract

ABSTRACT Theoretical and observational studies have suggested that ram-pressure stripping (RPS) by the intracluster medium can be enhanced during cluster interactions, boosting the formation of the ‘jellyfish’ galaxies. In this work, we study the incidence of galaxies undergoing RPS in 52 clusters of different dynamical states. We use optical data from the WINGS/OmegaWINGS surveys and archival X-ray data to characterize the dynamical state of our cluster sample, applying eight different proxies. We then compute the number of RPS candidates relative to the infalling population of blue late-type galaxies within a fixed circular aperture in each cluster. We find no clear correlation between the fractions of RPS candidates and the different cluster dynamical state proxies considered. These fractions also show no apparent correlation with cluster mass. To construct a dynamical state classification closer to a merging ‘sequence’, we perform a visual classification of the dynamical states of the clusters, combining information available in optical, X-ray, and radio wavelengths. We find a mild increase in the RPS fraction in interacting clusters with respect to all other classes (including post-mergers). This mild enhancement could hint at a short-lived enhanced RPS in ongoing cluster mergers. However, our results are not statistically significant due to the low galaxy numbers. We note this is the first homogeneous attempt to quantify the effect of cluster dynamical state on RPS using a large cluster sample, but even larger (especially wider) multiwavelength surveys are needed to confirm the results.