Cosmic evolution of the star formation efficiency in Milky Way-like galaxies
(2025) In Monthly Notices of the Royal Astronomical Society 538(4). p.2646-2659- Abstract
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... (More)
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.
(Less)
- author
- Segovia Otero, Álvaro LU ; Agertz, Oscar LU ; Renaud, Florent LU ; Kraljic, Katarina ; Romeo, Alessandro B. and Semenov, Vadim A.
- organization
- publishing date
- 2025-04-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- galaxies: star formation, ISM: structure, methods: numerical
- in
- Monthly Notices of the Royal Astronomical Society
- volume
- 538
- issue
- 4
- pages
- 14 pages
- publisher
- Oxford University Press
- external identifiers
-
- scopus:105001952044
- ISSN
- 0035-8711
- DOI
- 10.1093/mnras/staf423
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2025 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.
- id
- 693a3507-835e-4da5-8226-c6610c8a6b28
- date added to LUP
- 2025-12-05 11:26:42
- date last changed
- 2025-12-05 11:27:14
@article{693a3507-835e-4da5-8226-c6610c8a6b28,
abstract = {{<p>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, ε<sub>ff</sub>. During starbursts velocity dispersions can reach ∼50 km s<sup>−1</sup>, 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<sup>−1</sup>. Despite strongly evolving density and turbulence distributions over cosmic time, ε<sub>ff</sub> 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 (ε<sub>ff</sub>) ≈ 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 ε<sub>ff</sub> is intrinsically different from its observational estimates adopting tracers of star formation, e.g. Hα.</p>}},
author = {{Segovia Otero, Álvaro and Agertz, Oscar and Renaud, Florent and Kraljic, Katarina and Romeo, Alessandro B. and Semenov, Vadim A.}},
issn = {{0035-8711}},
keywords = {{galaxies: star formation; ISM: structure; methods: numerical}},
language = {{eng}},
month = {{04}},
number = {{4}},
pages = {{2646--2659}},
publisher = {{Oxford University Press}},
series = {{Monthly Notices of the Royal Astronomical Society}},
title = {{Cosmic evolution of the star formation efficiency in Milky Way-like galaxies}},
url = {{http://dx.doi.org/10.1093/mnras/staf423}},
doi = {{10.1093/mnras/staf423}},
volume = {{538}},
year = {{2025}},
}