Measuring the Effect of Ram Pressure on Star Formation in Infalling Galaxies

Abstract

Ram pressure stripping is a well-known galactic quenching mechanism capable of removing star-forming gas from a galaxy as it falls into a group or cluster. However, prior to stripping, ram pressure can induce brief periods of enhanced star formation by compressing the gas on the leading side of an infalling galaxy. Studies of this phenomenon have focused primarily on a unique population of galaxies for which a stripped tail of gas opposing the direction of motion is visible, known as jellyfish galaxies. The role of this effect in galaxy evolution overall is currently unknown. This thesis investigates the importance of ram pressure-induced star formation across all infalling galaxies to generalize our understanding of the effect. We use several metrics to measure the star formation asymmetries of a large sample of group and cluster galaxies in the Sloan Digital Sky Survey using $u$-band imaging from the Canada-France Imaging Survey as a tracer for star formation rate. We find that the distributions of star formation asymmetries of satellite galaxies are indistinguishable from those of a control sample of isolated field galaxies. Subdividing the sample by host halo mass and time since infall, we still find no environmental dependence of ram pressure as an enhancer of star formation. We conclude that any statistical star formation enhancement is small for infalling galaxies, suggesting that this effect is either uncommon or short-lived.