Physical properties and scaling relations of molecular clouds: The effect of stellar feedback

Research output: Contribution to journalArticle


Using hydrodynamical simulations of entire galactic discs similar to the Milky Way (MW), reaching 4.6 pc resolution, we study the origins of observed physical properties of giant molecular clouds (GMCs). We find that efficient stellar feedback is a necessary ingredient in order to develop a realistic interstellar medium, leading to molecular cloud masses, sizes, velocity dispersions, and virial parameters in excellent agreement withMWobservations. GMCscaling relations observed in the MW, such as the mass-size (M-R), velocity dispersion-size (σ-R), and the σ-RΣ relations, are reproduced in a feedback-driven ISM when observed in projection, with M∝R2.3 and σ∝R0.56.When analysed in 3D, GMC scaling relations steepen significantly, indicating potential limitations of our understanding of molecular cloud 3D structure from observations. Furthermore, we demonstrate how a GMC population's underlying distribution of virial parameters can strongly influence the scatter in derived scaling relations. Finally, we show that GMCs with nearly identical global properties exist in different evolutionary stages, where a majority of clouds being either gravitationally bound or expanding, but with a significant fraction being compressed by external ISM pressure, at all times.


External organisations
  • University of Oxford
  • University of Surrey
  • Chalmers University of Technology
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology


  • Galaxies:evolution, Galaxies:formation, Galaxies:ism, Galaxies:structure
Original languageEnglish
Pages (from-to)3167-3180
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - 2018 Sep 21
Publication categoryResearch