The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Oscar Agertz. Profile photo.

Oscar Agertz

Associate Professor / Senior university lecturer / Wallenberg Academy Fellow

Oscar Agertz. Profile photo.

Cosmic evolution of the star formation efficiency in Milky Way-like galaxies

Author

  • Álvaro Segovia Otero
  • Oscar Agertz
  • Florent Renaud
  • Katarina Kraljic
  • Alessandro B. Romeo
  • Vadim A. Semenov

Summary, in English

Current star formation models are based on the structure of the interstellar medium (ISM), yet the details on how local physics propagates to galactic-scale properties are still debated. To investigate this, we use VINTERGATAN, a high-resolution cosmological zoom-in simulation of a Milky Way-like galaxy. We study how the velocity dispersion and density structure of the cold neutral ISM on 50–100 pc scales evolve with redshift and quantify their impact on the star formation efficiency per free-fall time-scale, εff. During starbursts velocity dispersions can reach ∼50 km s−1, especially throughout last major merger events (1.3 < z < 1.5). After a merger-dominated phase (1 < z < 5), VINTERGATAN transitions into evolving secularly, featuring velocity dispersion levels of ∼10 km s−1. Despite strongly evolving density and turbulence distributions over cosmic time, εff at the resolution limit is found to change by only a factor of a few: from median efficiencies of 0.8 per cent at z > 1 to 0.3 per cent at z < 1. The mass-weighted average shows a universal (εff) ≈ 1 per cent, caused by an almost invariant virial parameter distribution in star-forming clouds. Changes in their density and turbulence levels are coupled, so the kinetic-to-gravitational energy ratio remains close to constant. We show that a theoretically motivated εff is intrinsically different from its observational estimates adopting tracers of star formation, e.g. Hα.

Department/s

  • Astrophysics
  • eSSENCE: The e-Science Collaboration

Publishing year

2025-04-01

Language

English

Pages

2646-2659

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

538

Issue

4

Document type

Journal article

Publisher

Oxford University Press

Topic

  • Astronomy, Astrophysics and Cosmology
  • Fusion, Plasma and Space Physics

Keywords

  • galaxies: star formation
  • ISM: structure
  • methods: numerical

Status

Published

ISBN/ISSN/Other

  • ISSN: 0035-8711