Tidal Truncation of Gas Replenishment and Global Suppression of Galactic Star Formation in Distant Clusters

Recent spectroscopic observations of galaxies in distant clusters haverevealed that the rate of star formation in star-forming galaxies issignificantly suppressed with respect to their counterparts in the field at asimilar redshift. It is, however, highly uncertain which physical processes areresponsible for this suppression. We present the results of a numericalinvestigation of how the global tidal field of a cluster dynamically influencesthe reservoir of halo gas surrounding a disk galaxy as it falls into thecluster from the surrounding field. We find that the tidal field of the clusterefficiently removes the halo gas from the galaxy, thereby halting its accretiononto the disk, and thus the fueling of star formation within. This effectivelytruncates the galaxy's star formation. We also find that this tidal truncationdoes not depend very strongly on the orbit of the disk with respect to thecenter of the cluster. These results suggest that the global tidal field of clusters is capable ofcausing a widespread and uniform suppression of star formation in galaxiesaccreted by the cluster. In light of these results, we discuss the importanceof this tidal truncation of the gas supply in the formation of S0 galaxies inclusters.Comment: 11 pages 4 figures,2001, PASJ,in pres