The GECKOS survey: Jeans anisotropic models of edge-on discs uncover the impact of dust and kinematic structures

¹ European Southern Observatory, Karl-Schwarzschild-Straße 2, Garching 85748, Germany
² Sydney Institute for Astronomy, School of Physics, A28, The University of Sydney, NSW 2006, Australia
³ School of Physics, University of New South Wales, NSW 2052, Australia
⁴ Sub-department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, United Kingdom
⁵ Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, United Kingdom
⁶ Centre for Extragalactic Astronomy, Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom
⁷ Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, E-38205 La Laguna, Tenerife, Spain
⁸ Departamento de Astrofísica, Universidad de La Laguna, Av. del Astrofísico Francisco Sánchez s/n, E-38206 La Laguna, Tenerife, Spain
⁹ Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstr. 1, 81679 München, Germany
¹⁰ Department of Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria
¹¹ Astrophysics Research Group, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
¹² Cardiff Hub for Astrophysics Research & Technology, School of Physics & Astronomy, Cardiff University, Queens Buildings, Cardiff CF24 3AA, United Kingdom
¹³ Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218 Hawthorn, VIC 3122, Australia
¹⁴ Homer L. Dodge Department of Physics & Astronomy, University of Oklahoma, 440 W. Brooks St, Norman, OK 73019, USA
¹⁵ School of Mathematical and Physical Sciences, Macquarie University, NSW 2109, Australia
¹⁶ Macquarie University Astrophysics and Space Technologies Research Centre, Sydney, NSW 2109, Australia
¹⁷ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA

^⋆ Corresponding author: trut2989@uni.sydney.edu.au

Received: 15 July 2025
Accepted: 9 September 2025

Abstract

The central regions of disc galaxies host a rich variety of stellar structures: nuclear discs, bars, bulges, and boxy-peanut bulges. These components are often difficult to disentangle, both photometrically and kinematically, particularly in star-forming galaxies where dust obscuration and complex stellar motions complicate interpretation. In this work, we used data from the GECKOS-MUSE survey to investigate the impact of dust on axisymmetric Jeans Anisotropic Multi-Gaussian Expansion (JAM) models and assess their ability to recover kinematic structures in edge-on disc galaxies. We constructed JAM models for a sample of seven edge-on (i ⪆ 85°) galaxies that span a range of star formation rates, dust content, and kinematic complexity. We find that when dust is appropriately masked, the disc regions of each galaxy are fit to χ_reduced² ≤ 5. We analysed 2D residual velocity fields to identify signatures of non-axisymmetric structure. We find that derived dynamical masses are constant within 10% for each galaxy across all dust masking levels. In NGC 3957, a barred boxy galaxy in our sample, we identified velocity residuals that persist even under aggressive dust masking, aligned with bar orbits and supported by photometric bar signatures. We extended this analysis to reveal a bar in IC 1711 and a possible side-on bar in NGC 0522. Our results highlight both the capabilities and limitations of JAM in dusty, edge-on systems and attempt to link residual velocities to known non-axisymmetric kinematic structure.