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\(_\odot\) gas phase mass resolution, \(\sim\)0.1 pc spatial resolution) the multiphase interstellar medium with a non-equilibrium chemical heating/cooling network at temperatures below 10\(^4\) 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 (\(T_\mathrm{gas} < 300\) K) filamentary clouds with self-similar internal structures. The clouds have masses of \(10^{2.6}\)-\(10^{5.6}\) M\(_\odot\) with a power-law mass function, \(\mathrm{ d}N/\mathrm{ d}M \propto M^\alpha\) with \(\alpha = -1.78 (\,\pm \,0.08)\). 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 \(\sim\)3.5 Myr. Clouds with peak masses below \(10^4\) M\(_\odot\) follow a power-law relation with their average lifetime \(\tau _\mathrm{life} \propto M^{0.3}_\mathrm{max}\) 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.