Published Article: The masses, structure, and lifetimes of cold clouds in a high-resolution simulation of a low-metallicity starburst
In this article, we study the formation and evolution of cold gas clouds in a high-resolution dwarf merger simulation. The clouds have masses and sizes that are in good agreement with observations. This study is part of the GRIFFIN project.
Abstract: We present an analysis of the cold gas phase in a low-metallicity starburst generated in a high-resolution hydrodynamical simulation of a gas-rich dwarf galaxy merger as part of the GRIFFIN project. The simulations resolve (4 M⊙ gas phase mass resolution, ∼0.1 pc spatial resolution) the multiphase interstellar medium with a non-equilibrium chemical heating/cooling network at temperatures below 104 K. Massive stars are sampled individually and interact with the interstellar medium (ISM) through the formation of H II regions and supernova explosions. In the extended starburst phase, the ISM is dominated by cold (Tgas<300 K) filamentary clouds with self-similar internal structures. The clouds have masses of 102.6-105.6 M⊙ with a power-law mass function, dN/dM∝Mα with α=−1.78(±0.08). They also follow the Larson relations, in good agreement with observations. We trace the lifecycle of the cold clouds and find that they follow an exponential lifetime distribution and an e-folding time of ∼3.5 Myr. Clouds with peak masses below 104 M⊙ follow a power-law relation with their average lifetime τlife∝M0.3max which flattens out for higher cloud masses at <10 Myr. A similar relation exists between cloud size at peak mass and lifetime. This simulation of the evolution of a realistic galactic cold cloud population supports the rapid formation and disruption of star-forming clouds by stellar radiation and supernovae on a time-scale less than 10 Myr.