Shattering cold gas into tiny cloudlets

Abstract

Absorption studies of galaxies and galaxy clusters at high-redshift have unexpectedly found that their halos are also full of cold gas, in addition to the theoretically-predicted virialized plasma. These observations typically indicate a relatively modest total fraction of cold gas (~10^{-4}% by volume), yet find it in essentially every sightline through the galaxy. I will show that cold gas clouds are prone to “shattering” into tiny fragments, and that the resulting small clouds naturally reproduce the large area-covering fractions and small volume-filling fractions inferred from observations. This same effect enhances the drag force coupling the dynamics of cold and hot gasses; I will also discuss potential applications to entrainment of cold gas in galaxy winds, and the possibility of using cold gas to constrain the kinematics of the hot ICM.