The stellar velocity dispersion in nearby spirals: radial profiles and correlations

• Published in: Monthly notices of the Royal Astronomical Society Vol. 489; no. 3; pp. 3797 - 3809
• Main Authors: Mogotsi, Keoikantse Moses, Romeo, Alessandro B
• Format: Journal Article
• Language: English
• Published: Oxford University Press 26-08-2019
• Subjects: galaxies: ISM-galaxies: kinematics and dynamics; galaxies: star formation; galaxies: structure; instabilities; ISM: kinematics and dynamics; galaxies: structure; galaxies: kinematics and dynamics; instabilities; galaxies: ISM; ISM: kinematics and dynamics; galaxies: star formation
• ISSN: 0035-8711; 1365-2966; 1365-2966
• DOI: 10.1093/mnras/stz2370

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.