Mapping hydrodynamical and gravitational effects on galaxies around rilaments with citizen science

Abstract

This thesis explores the application of citizen science via the Zooniverse platform to identify jellyfish galaxies (JF) and mergers within Cluster A1644 at z = 0.0467. Utilizing public classifications obtained through visual inspection, we establish distinct criteria for these identifications and analyze the pre-processing of galaxies to understand the quenching mechanism’s variations based on the distance to the cluster center. Our analysis, conducted on a sample of 403 galaxies from the cluster, reveals a 21% overlap between expert classifications and the pure sample for ram pressure stripping candidates. The complete sample for ram pressure stripping (RPS) candidates shows a 60% overlap with expert classifications. For merger candidates, a 15% agreement with the expert sample is observed. Interestingly, Zooniverse-identified merger candidates, on average, have a filament distance 2.10 times closer than that of the average cluster galaxy. This trend reverses when considering expert-classified mergers. No notable disparities in galaxy filament distances are observed between JF galaxies and other galaxies, whether classified by citizen scientists or experts in ram pressure stripping. However, for galaxies beyond 1R200, JF galaxies exhibit a filament distance approximately 1.20 Mpc greater than that of other cluster galaxies. While the significance of this finding is modest, it may suggest a potential shielding effect for galaxies in close proximity to filaments, a phenomenon observed in simulations. Given the preliminary nature of this study, further exploration could be conducted across additional clusters in the Zooniverse to better understand the influence of filaments.