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

Keoikantse Moses Mogotsi; Alessandro B. Romeo

doi:10.1093/mnras/stz2370

paper

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

arXiv:1804.10119 · 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 $σ_{R}$ and present reliable radial profiles of $σ_{R}$ as well as accurate measurements of $⟨ σ_{R} ⟩$ , the radial average of $σ_{R}$ over one effective (half-light) radius. We show that there is a trend for $σ_{R}$ to increase with decreasing $R$ , that $⟨ σ_{R} ⟩$ correlates with stellar mass ( $M_{⋆}$ ) and tested correlations with other galaxy properties. The most significant and strongest correlation is the one with $M_{⋆}$ : $⟨ σ_{R} ⟩ \propto M_{⋆}^{0.5}$ . This tight scaling relation is applicable to spiral galaxies of type Sa $\mbox{--}$ Sd and stellar mass $M_{\star}\approx10^{9.5}\mbox{--}10^{11.5}\ \mbox{M}_{\odot}$. Simple models that relate $σ_{R}$ to the stellar surface density and disc scale length roughly reproduce that scaling, but overestimate $⟨ σ_{R} ⟩$ significantly.

arXiv commentMNRAS, in press

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

Abstract

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