Publication Date:
2021-10-28
Description:
A simple model for star formation based on supernova (SN) feedback and gravitational heating via the collapse of perturbations in gravitationally unstable disks reproduces the Schmidt-Kennicutt relation between the star formation rate (SFR) per unit area, ΣSFR, and the gas surface density, Σg, remarkably well. The gas velocity dispersion, σg, is derived self-consistently in conjunction with ΣSFR and is found to match the observations. Gravitational instability triggers ‘gravito-turbulence’ at the scale of the least stable perturbation mode, boosting σg at $Sigma _{g}gtrsim , Sigma _{g}^extrm {thr}=50, {
m M}_odot , {
m pc}^{-2}$, and contributing to the pressure needed to carry the disk weight vertically. ΣSFR is reduced to the observed level at $Sigma _{g}gtrsim , Sigma _{g}^extrm {thr}$, whereas at lower surface densities, SN feedback is the prevailing energy source. Our proposed star formation recipes require efficiencies of order 1 per cent, and the Toomre parameter, Q, for the joint gaseous and stellar disk is predicted to be close to the critical value for marginal stability for $Sigma _{g}lesssim , Sigma _{g}^extrm {thr}$, spreading to lower values and larger gas velocity dispersion at higher Σg.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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