The effects of metallicity, UV radiation and non-equilibrium chemistry in high-resolution simulations of galaxies

Understand

We present a series of hydrodynamic simulations of isolated galaxies with stellar mass of $10^{9} \, \rm{M}_{\odot}$.

• The models use a resolution of $750 \, \rm{M}_{\odot}$ per particle and include a treatment for the full non-equilibrium chemical evolution of ions and molecules (157 species in total), along with gas cooling rates computed self-consistently using the non-equilibrium abundances.
• We compare these to simulations evolved using cooling rates calculated assuming chemical (including ionisation) equilibrium, and we consider a wide range of metallicities and UV radiation fields, including a local prescription for self-shielding by gas and dust.
• We find higher star formation rates and stronger outflows at higher metallicity and for weaker radiation fields, as gas can more easily cool to a cold (few hundred Kelvin) star forming phase under such conditions.