Description:

Zach Hafen
Title: Using Galaxy Formation Simulations to Develop Diagnostics of CGM Gas Flows

Abstract: Recent galaxy formation simulations provide an unprecedented amount of predictive power, informing observations of galaxies and enabling insight into their evolution. One area of crucial study for both simulations and observations is the circum-galactic medium (CGM), the area immediately surrounding galaxies. Among the gas flows passing through the CGM, gas falling into galaxies feeds galaxy growth, while gas expelled from galaxies regulates galaxy growth. The interplay of these processes is key for understanding the evolution of galaxies. In this talk I discuss efforts to use the FIRE (Feedback In Realistic Environments) simulations to place observations of CGM gas flows in a physical setting, increasing the power of CGM observations as an astrophysical tool.

Alex Richings
Title: Non-equilibrium chemistry in simulations of galaxy formation

Abstract: Simulations of galaxies often assume chemical equilibrium, where the chemical reactions between ions and molecules have reached a steady state. However, this assumption may not be valid if the physical conditions of the gas are evolving rapidly. I will present a chemical model that we have developed to follow the non-equilibrium evolution of ions and molecules, which we have incorporated into hydrodynamic simulations of galaxies. We applied this model to simulations of isolated disc galaxies with different metallicities and UV radiation fields, and compared these to simulations that assume chemical equilibrium. We found that the total star formation rate is higher at higher metallicity and for weaker radiation fields. In contrast, non-equilibrium chemistry does not strongly influence the total star formation rate or outflow properties of the galaxy. However, it does affect the abundances of individual chemical species, for example in molecular outflows

Pizza will be available.