The global star formation law by supernova feedback

Avishai Dekel*, Kartick C. Sarkar, Fangzhou Jiang, Frederic Bournaud, Mark R. Krumholz, Daniel Ceverino, Joel R. Primack

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

We address a simple model where the Kennicutt-Schmidt (KS) relation between the macroscopic densities of star formation rate (SFR, ρsfr) and gas (n) in galactic discs emerges from self-regulation of the SFR via supernova feedback. It arises from the physics of supernova bubbles, insensitive to the microscopic SFR recipe and not explicitly dependent on gravity. The key is that the filling factor of SFR-suppressed supernova bubbles self-regulates to a constant, f ∼ 0.5. Expressing the bubble fading radius and time in terms of n, the filling factor is f ∝ S ns with s = 1.5, where S is the supernova rate density. A constant f thus refers to ρsfr ∝ n1.5, with a density-independent SFR efficiency per free-fall time ∼0.01. The self-regulation to f ∼ 0.5 and the convergence to a KS relation independent of the local SFR recipe are demonstrated in cosmological and isolated-galaxy simulations using different codes and recipes. In parallel, the spherical analysis of bubble evolution is generalized to clustered supernovae, analytically and via simulations, yielding s = 1.5 ± 0.5. An analysis of photoionized bubbles about presupernova stars yields a range of KS slopes but the KS relation is dominated by the supernova bubbles. Superbubble blowouts may lead to an alternative self-regulation by outflows and recycling. While the model is oversimplified, its simplicity and validity in the simulations may argue that it captures the origin of the KS relation.

Original languageEnglish
Pages (from-to)4753-4778
Number of pages26
JournalMonthly Notices of the Royal Astronomical Society
Volume488
Issue number4
DOIs
StatePublished - 1 Oct 2019

Bibliographical note

Publisher Copyright:
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society

Keywords

  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: ISM
  • Stars: formation
  • Supernovae: general

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