Misc,
The effect of non-equilibrium metal cooling on the interstellar medium
(2017)cite arxiv:1710.01302Comment: Submitted to MNRAS.
Abstract
By using a novel interface between the modern smoothed particle hydrodynamics
code GASOLINE2 and the chemistry package KROME, we follow the hydrodynamical
and chemical evolution of an isolated galaxy. In order to assess the relevance
of different physical parameters and prescriptions, we constructed a suite of
ten simulations, in which we vary the chemical network (primordial and metal
species), how metal cooling is modelled (non-equilibrium versus equilibrium),
the initial gas metallicity (from ten to hundred per cent solar), and how
molecular hydrogen forms on dust. This is the first work in which metal
injection from supernovae, turbulent metal diffusion, and a metal network with
non-equilibrium metal cooling are self-consistently included in a galaxy
simulation. We find that modelling the chemical evolution of several metal
species and the corresponding non-equilibrium metal cooling has important
effects on the thermodynamics of the gas, the chemical abundances, and the
appearance of the galaxy: the gas is typically warmer, has a larger molecular
gas mass fraction, and has a smoother disc. We also conclude that, at
relatively high metallicity, the choice of molecular hydrogen formation rates
on dust is not crucial. Moreover, we confirm that a higher initial metallicity
produces a colder gas and a larger fraction of molecular gas, with the
low-metallicity simulation best matching the observed molecular
Kennicutt-Schmidt relation. Finally, our simulations agree quite well with
observations which link star formation rate to metal emission lines.
