2022MNRAS.509.2979N

A simple model for star formation based on supernova (SN) feedback and gravitational heating via the collapse of perturbations in gravitationally unstable discs reproduces the Schmidt-Kennicutt relation between the star formation rate (SFR) per unit area, Σ_SFR, and the gas surface density, Σ_g, remarkably well. The gas velocity dispersion, σ_g, is derived self-consistently in conjunction with Σ_SFR and is found to match the observations. Gravitational instability triggers 'gravitoturbulence' at the scale of the least stable perturbation mode, boosting σ_g at Σ_g≳Σ_g^thr=50 M_☉ pc_^–2, and contributing to the pressure needed to carry the disc weight vertically. Σ_SFR is reduced to the observed level at Σ_g≳Σ_g^thr, whereas at lower surface densities, SN feedback is the prevailing energy source. Our proposed star formation recipes require efficiencies of the order of 1 per cent, and the Toomre parameter, Q, for the joint gaseous and stellar disc is predicted to be close to the critical value for marginal stability for Σ_g≲Σ_g^thr, spreading to lower values and larger gas velocity dispersion at higher Σ_g.