http://arxiv.org/abs/1804.10119
The stellar velocity dispersion, $\sigma$, 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, and present reliable radial profiles of $\sigma_{R}$ as well as accurate measurements of $\langle\sigma_{R}\rangle$, the radial average of $\sigma_{R}$ over one effective (half-light) radius. We show that there is a trend for $\sigma_{R}$ to increase with decreasing $R$, consistent with a process of disc heating mediated by local gravitational instabilities and radial inflow, and that $\langle\sigma_{R}\rangle$ correlates with stellar mass ($M_{\star}$), molecular gas mass ($M_{\mathrm{mol}}$), star formation rate ($\mathrm{SFR}$) and other galaxy properties. The most significant and strongest correlation is the one with $M_{\star}$: $\log\langle\sigma_{R}\rangle = 0.45\,\log(M_{\star}/\mbox{M}{\odot})-2.77\;[\mbox{km\,s}^{-1}]$, which has a rms scatter of 0.10 dex (26%). This tight scaling relation is applicable to spiral galaxies of type Sa–Sd and stellar mass $M{\star}\approx10^{9.5}\mbox{–}10^{11.5}\ \mbox{M}{\odot}$. Simple models that relate $\sigma{R}$ to the stellar surface density and disc scale length roughly reproduce that scaling, but overestimate $\langle\sigma_{R}\rangle$ significantly.
K. Mogotsi and A. Romeo
Fri, 27 Apr 18
-34/64
Comments: Submitted to MNRAS
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