I am an astronomer/astrophysicist at Northwestern University. Specifically, I work at CIERA, in prof. Claude-André Faucher-Giguère's research group. Before that, I worked in prof. Joop Schaye's group at Leiden Observatory, where I obtained my PhD. I study how diffuse gas around galaxies drives/affects the formation and evolution of those galaxies.
When I'm not doing research, I enjoy climbing/bouldering, board games, puzzles, and hiking when I get the chance.
The Universe contains galaxies of many shapes and sizes, including our own Milky Way. These galaxies are surrounded by haloes of gas and dark matter, and those haloes are in turn connected by sheets and filaments of dark matter and gas which form the ‘cosmic web’. The gas in the cosmic web and galaxy haloes is diffuse, and therefore often difficult to observe. However, it plays a crucial role in the formation and evolution of galaxies. The gas in galaxy haloes, and ultimately in the cosmic web, is needed to fuel star formation within galaxies. Though galaxies contain gas as well as stars, this gas is insufficient to maintain star formation as long as we know they must.
The galaxies also affect the gas in their haloes: when stars form in a galaxy, they eventually die. Massive stars, which are also relatively short-lived, can explode as supernovae. These supernova explosions can generate outflows, where gas is ejected from the galaxy into its halo. These outflows may even escape the halo altogether and join the cosmic web, possibly sweeping up some of the halo gas on the way.
Besides stars, supermassive black holes that live at the centers of galaxies like our own Milky Way can also drive outflows. This can happen when gas falls into this black hole. Although nothing can escape from inside a black hole, the extreme forces near a black hole can release a lot of energy from the infalling gas. This energy release can drive outflows out of the galaxy, and perhaps even its halo.
I use simulations of dark matter, gas, stars and black holes (currently FIRE, previously EAGLE) to study this diffuse gas around and between galaxies. Some of this gas has been detected in observations, but it has been especially hard to find the hotter gas around roughly Milky-Way-mass galaxies and in the cosmic web. My research has focused on possible ways to detect this gas (e.g., with planned and proposed future instruments), and on comparing simulation predictions to some observations we currently do have.
My latest paper, on Ne VIII absorption in galaxy haloes: arXiv:2401.08776