The SAMI Galaxy Survey: mass-kinematics scaling relations

Abstract

We use data from the Sydney-AAO Multi-object Integral-field spectroscopy (SAMI) Galaxy Survey to study the dynamical scaling relation between galaxy stellar mass $M_{\ast }$ and the general kinematic parameter $S_K=\sqrt{K{V}_{rot}^2+\ddot{I}{ƒ}^2}$ that combines rotation velocity $V_{rot}$ and velocity dispersion $\ddot{I}ƒ$. We show that the $\log M_{\ast }-\log S_K$ relation: (1)~is linear above limits set by properties of the samples and observations; (2)~has slightly different slope when derived from stellar or gas kinematic measurements; (3)~applies to both early-type and late-type galaxies and has smaller scatter than either the Tully-Fisher relation ($\log M_{\ast }-\log V_{rot}$) for late types or the Faber-Jackson relation ($\log M_{\ast }-\log \ddot{I}ƒ$) for early types; and (4)~has scatter that is only weakly sensitive to the value of $K$, with minimum scatter for $K$ in the range 0.4 and 0.7. We compare $S_K$ to the aperture second moment (the `aperture velocity dispersion') measured from the integrated spectrum within a 3-arcsecond radius aperture ($\ddot{I}{ƒ}_{3^{\prime \prime }}$). We find that while $S_K$ and $\ddot{I}{ƒ}_{3^{\prime \prime }}$ are in general tightly correlated, the $\log M_{\ast }-\log S_K$ relation has less scatter than the $\log M_{\ast }-\log \ddot{I}{ƒ}_{3^{\prime \prime }}$ relation.

14 pages, 8 figures, Accepted 2019 May 22. Received 2019 May 18; in original form 2019 January 6