My research is focused on understanding the flow of gas into and out of galaxies, and the effects of these flows on galaxy evolution.  Because stars form out of cool gas, the inflow (or accretion) of such gas onto galaxies provides an important source of fuel for further star formation.  Once these stars form, however, they are so luminous that their radiation can push away the surrounding gas.  This pressure, along with the energy released during the explosive deaths of these stars, may remove much of the cool gas from the galaxy’s star-forming regions, and may push it out into the galaxy’s outskirts (halo), or even beyond the galaxy’s gravitational sphere of influence.  This process is termed ‘outflow’, and reduces the galaxy’s immediate fuel supply.  However, if the gas remains within the galaxy’s halo, it may eventually fall back again toward the stars, providing further fuel, and allowing the whole process to repeat.  This sequence of events is called the `baryon cycle’, and I study gas around distant galaxies in a variety of stages of this cycle. For instance:

• Accretion: on occasion my collaborators and I detect gas infalling onto its host galaxy. Check out this link for details.

• Outflow: mostly, though, we detect gas flowing away from galaxies.

• Extending over large scales: we are also able to map the gas distribution around a type of high-redshift galaxy called a Damped Lyα system.