The effective stability parameter for two-component galactic discs: is 1/Q ~ 1/Q_stars + 1/Q_gas ?
Journal article, 2011

The Wang-Silk approximation, Q-1≈Q-1stars+Q-1gas, is frequently used for estimating the effective Q parameter in two-component discs of stars and gas. Here we analyse this approximation in detail, and show how its accuracy depends on the radial velocity dispersions and Toomre parameters of the two components. We then propose a much more accurate but still simple approximation for the effective Q parameter, which further takes into account the stabilizing effect of disc thickness. Our effective Q parameter is a natural generalization of Toomre's Q, and as such can be used in a wide variety of contexts, e.g. for predicting star formation thresholds in galaxies or for measuring the stability level of galactic discs at low and high redshifts.

Author

Alessandro Romeo

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

Joachim Wiegert

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 416 2 1191-1196

Subject Categories

Astronomy, Astrophysics and Cosmology

Roots

Basic sciences

DOI

10.1111/j.1365-2966.2011.19120.x

More information

Created

10/7/2017