Star formation is the driver of galaxy evolution. Understanding the properties of the cold, star-forming gas in the interstellar medium (ISM) is therefore of crucial importance. In this talk, I will present recent developments in high-resolution (sub-parsec) hydrodynamical simulations of the stellar feedback-regulated ISM and their predictions for chemical properties and line emissions, leveraging a novel hybrid method for ISM chemistry that captures the non-equilibrium effects of molecular hydrogen (H2). I will show that steady-state chemistry significantly over-predicts the abundances of H2 but not carbon monoxide (CO), leading to a reduced conversion factor (X_CO), especially at low metallicities where the H2 formation time becomes much longer than the dynamical time. On parsec scales, X_CO varies by orders of magnitude from place to place, primarily driven by the transition from atomic carbon to CO. Finally, I will present simulations combining ISM chemistry and dust evolution (sputtering and dust growth) and show how dust growth helps explain the observed CO luminosity in the low-metallicity WLM dwarf galaxy. Our results have important implications for galaxies observed in the early universe by JWST.
Bio:
Chia-Yu Hu is currently an Assistant Professor at the Institute of Astrophysics at the National Taiwan University, studying various problems in astrophysics using high-performance computer simulations. Research topics include the interstellar medium, stellar feedback, galactic winds, turbulence modeling, and numerical methods.
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2025-08-06T15:00:002025-08-06T16:00:00Dwarf galaxies as laboratories for the interstellar medium at low metallicityEvent Information:
Abstract:
Star formation is the driver of galaxy evolution. Understanding the properties of the cold, star-forming gas in the interstellar medium (ISM) is therefore of crucial importance. In this talk, I will present recent developments in high-resolution (sub-parsec) hydrodynamical simulations of the stellar feedback-regulated ISM and their predictions for chemical properties and line emissions, leveraging a novel hybrid method for ISM chemistry that captures the non-equilibrium effects of molecular hydrogen (H2). I will show that steady-state chemistry significantly over-predicts the abundances of H2 but not carbon monoxide (CO), leading to a reduced conversion factor (X_CO), especially at low metallicities where the H2 formation time becomes much longer than the dynamical time. On parsec scales, X_CO varies by orders of magnitude from place to place, primarily driven by the transition from atomic carbon to CO. Finally, I will present simulations combining ISM chemistry and dust evolution (sputtering and dust growth) and show how dust growth helps explain the observed CO luminosity in the low-metallicity WLM dwarf galaxy. Our results have important implications for galaxies observed in the early universe by JWST.
Bio:
Chia-Yu Hu is currently an Assistant Professor at the Institute of Astrophysics at the National Taiwan University, studying various problems in astrophysics using high-performance computer simulations. Research topics include the interstellar medium, stellar feedback, galactic winds, turbulence modeling, and numerical methods.
Learn More:
Read his faculty page: Chia-Yu Hu
Read his Github page: Chia-Yu Hu
Event Location:
HENN 318
