The turbulent fragmentation of the interstellar medium: The impact of
  metallicity on global star formation
  We study the influence of gas metallicity, turbulence, and non-equilibrium
chemistry on the evolution of the two-phase interstellar medium (warm and cold
atomic phases), and thereby constrain the initial conditions for star formation
prevailing in turbulent gas. We perform high-resolution simulations in three
dimensions, including a realistic non-equilibrium treatment of the ionization
state of the gas, and examine both driven and decaying turbulence. This allows
us to explore variations in the metallicity Z. In this paper, we study solar
metallicity, Z=Z_sun, and low metallicity, Z=1d-3 Z_sun, gas. For driven,
large-scale turbulence, we find that the influence of the metallicity on the
amount of mass in the cold gas component is small. However, in decaying
turbulent conditions this picture is much changed. While cold regions survive
in the case of solar metallicity, they are quickly heated and dispersed in
low-metallicity gas. This result suggests that star formation can be suppressed
in environments of low metallicity, unless a strong turbulent driver is acting
on time scales shorter than a few turbulent crossing times. Inter alia this
finding could explain the overall inefficient star formation as well as the
burst-like mode of star formation found in metal-poor, gas-rich systems like
dwarf galaxies.
