The interstellar medium and star formation on kpc size scales
Monthly Notices of the Royal Astronomical Society
Oxford University Press on behalf of the Royal Astronomical Society
© 2015 The Author. This is the final version of the article. Available from Oxford University Press via the DOI in this record.
By resimulating a region of a global disc simulation at higher resolution, we resolve and study the properties of molecular clouds with a range of masses from a few hundreds of M⊙ to 106 M⊙. The purpose of our paper is twofold, (i) to compare the interstellar medium (ISM) and Giant Molecular Clouds (GMCs) at much higher resolution compared to previous global simulations, and (ii) to investigate smaller clouds and characteristics such as the internal properties of GMCs which cannot be resolved in galactic simulations. We confirm the robustness of cloud properties seen in previous galactic simulations, and that these properties extend to lower mass clouds, though we caution that velocity dispersions may not be measured correctly in poorly resolved clouds. We find that the properties of the clouds and ISM are only weakly dependent on the details of local stellar feedback, although stellar feedback is important to produce realistic star formation rates and agreement with the Schmidt–Kennicutt relation. We study internal properties of GMCs resolved by 104–105 particles. The clouds are highly structured, but we find clouds have a velocity dispersion radius relationship which overall agrees with the Larson relation. The GMCs show evidence of multiple episodes of star formation, with holes corresponding to previous feedback events and dense regions likely to imminently form stars. Our simulations show clearly long filaments, which are seen predominantly in the interarm regions, and shells.
I would like to thank the referee for a constructive report, which has helped significantly improve this paper. The calculations for this paper were performed on the DiRAC machine ‘Complexity’, and the supercomputer at Exeter, a DiRAC jointly funded by STFC, the Large Facilities Capital Fund of BIS, and the University of Exeter. CLD acknowledges funding from the European Research Council for the FP7 ERC starting grant project LOCALSTAR. CLD thanks Ian Bonnell for providing data for Fig. 11, and Jim Pringle, Sarah Ragan and Ana Duarte-Cabral for useful comments and discussions. Several figures in this paper were produced using SPLASH (Price 2007).
Vol. 447, No. 4, pp. 3390-3401