ABSTRACT
The stellar velocity dispersion, σ, is a quantity of crucial importance for spiral galaxies, where it enters fundamental dynamical processes such as gravitational instability and disc heating. Here we analyse a sample of 34 nearby spirals from the Calar Alto Legacy Integral Field Area (CALIFA) spectroscopic survey, deproject the line-of-sight σ to σR, and present reliable radial profiles of σR as well as accurate measurements of 〈σR〉, the radial average of σR over one effective (half-light) radius. We show that there is a trend for σR to increase with decreasing R, that 〈σR〉 correlates with stellar mass (M⋆), and tested correlations with other galaxy properties. The most significant and strongest correlation is the one with M⋆: |$\langle \sigma _{R}\rangle \propto M_{\star }^{0.5}$|. This tight scaling relation is applicable to spiral galaxies of type Sa–Sd and stellar mass M⋆ ≈ 109.5–1011.5 M⊙. Simple models that relate σR to the stellar surface density and disc scale length roughly reproduce that scaling, but overestimate 〈σR〉 significantly.