The GECKOS Survey: Classifying kinematic structures in edge-on galaxies through JAM modelling

In this talk, I will present early results from the GECKOS survey in a study that aims to create robust classifications of disc galaxy central kinematic components. We build on the stellar kinematic Gauss-Hermite velocity maps as tracers of galactic central structure by creating axisymmetric Jeans Anisotropic MGE (JAM) models for the available GECKOS sample. While components such as "bulges" and nuclear discs may be included in JAM with careful treatment of the surface brightness and mass gaussians, the array of possible stellar bar structure in disc galaxies is non-axisymmetric and fundamentally cannot be captured by a JAM model. By subtracting these models from the highly spatially resolved input velocity fields provided by MUSE, we disentangle, classify, and gain deeper understanding of the central structures from the residuals. Further, we combine our kinematic results with available photometric evidence to estimate the size of the bars we detect. Beyond bars, we see a wide range of residual structures. Taking these structures in combination with high-order Gauss-Hermite moments we search for, but find no evidence of classical bulges in the sample analysed so far. We conclude that Milky Way-like galaxies host a wide array of central kinematic components, and the high dispersion often seen in the centre of these galaxies is not necessarily indicative of a simple classical bulge.