The Effect of Cosmic Web Filaments on Quenching in Galaxy Clusters

Abstract

Environment plays an important role in the evolution of galaxies. In particular, denser environments, such as galaxy clusters and large-scale field filaments of the cosmic web have been found to reduce star formation in galaxies. The intersection of these environments provides an interesting regime of study. We investigate how cosmic filaments impact the quenching of galaxies within one virial radius of 324 simulated clusters. We use hydrodynamic runs from The Three Hundred Project along with the cosmic web extractor DisPerSE to track filaments and the structure finder VELOCIraptor to identify halos hosting galaxies. Limited by the resolution of the simulation, we examine star formation indirectly by way of galaxy colour and cold gas fraction. We find that cluster galaxies residing closer to filaments tend to be star-forming, bluer, and contain more cold gas than their counterparts further away from filaments. This is in stark contrast with galaxies residing outside of clusters, where galaxies close to filaments show clear signs of density related pre-processing. Careful examination of flows around and into cluster galaxies strongly suggests that the colder, dynamically coherent hydrodynamic streams along intra-cluster filaments partially shield galaxies close to them from strangulation by the hot, dense intra-cluster medium. These streams, in addition to the reduced density contrast of intra-cluster filaments with the intra-cluster medium, also limit the ram pressure stripping experienced by cluster galaxies. We further examine stripping in the context of gas disturbances in phase space to create a classification for wet and dry galaxies.