Tidal truncation of gas replenishment and global suppression of galactic star formation in distant clusters

Recent spectroscopic observations of galaxies in distant clusters have reve aled that the rate of star formation in star-forming galaxies is significan tly suppressed with respect to their counterparts in the field at a similar redshift. It is, however, highly uncertain which physical processes are re sponsible for this suppression. We present the results of a numerical inves tigation of how the global tidal field of a cluster dynamically influences the reservoir of halo gas surrounding a disk galaxy as it falls into the cl uster from the surrounding field. We find that the tidal field of the clust er efficiently removes the halo gas from the galaxy, thereby halting its ac cretion onto the disk, and thus the fueling of star formation within. This effectively truncates the galaxy's star formation. We also find that this t idal truncation does not depend very strongly on the orbit of the disk with respect to the center of the cluster. These results suggest that the globa l tidal field of clusters is capable of causing a widespread and uniform su ppression of star formation in galaxies accreted by the cluster. In light o f these results, we discuss the importance of this tidal truncation of the gas supply in the formation of SO galaxies in clusters.