Photometric and kinematic DiskFit models of four nearby spiral galaxies

Abstract

We present optical $\textit{BVRI}$ photometry, H$\alpha$ IFU velocity fields, and H$\alpha$ long-slit rotation curves for a sample of four nearby spiral galaxies having a range of morphologies and inclinations. We show that the $\texttt{DiskFit}$ code can be used to model the photometric and kinematic data of these four galaxies and explore how well the photometric data can be decomposed into structures like bars and bulges and to look for non-circular motions in the kinematic data. In general, we find good agreement between our photometric and kinematic models for most parameters. We find the best consistency between our photometric and kinematic models for NGC 6674, a relatively face-on spiral with clear and distinct bulge and bar components. We also find excellent consistency for NGC 2841, and find a bar $\sim$10$^{\circ}$ south of the disc major axis in the inner 20''. Due to geometric effects caused by its high inclination, we find the kinematic model for NGC 2654 to be less accurate than its photometry. We find the bar in NGC 2654 to be roughly parallel to the major axis of the galaxy. We are unable to photometrically model our most highly inclined galaxy, NGC 5746, with $\texttt{DiskFit}$ and instead use the galaxy isophotes to determine that the system contains a bar $\sim$5$^{\circ}$ to $\sim$10$^{\circ}$ east of the disc major axis. The high inclination and extinction in this galaxy also prevent our kinematic model from accurately determining parameters about the bar, though the data are better modeled when a bar is included.