Breaking the Blend: A multi-tracer kinematic decomposition method for IFS data applied to disentangling the AGN outflow and circumnuclear ring in NGC 5728 with JWST

Oscar Veenema, Niranjan Thatte, Dimitra Rigopoulou, Richard I. Davies, Miguel Pereira-Santaella, Ismael García-Bernete, Almudena Alonso-Herrero, Anelise Audibert, Enrica Bellocchi, Andrew J. Bunker, Françoise Combes, Tanio Díaz Santos, Fergus R. Donnan, Donaji Esparza-Arredondo, Federico Esposito, Santiago García-Burillo, Begoña García-Lorenzo, Omaira Gonzalez Martin, Laura Hermosa Muñoz, Erin K. S. Hicks, Sebastian F. Hönig, Masatoshi Imanishi, Alvaro Labiano, Nancy A. Levenson, Enrique Lopez-Rodriguez, Cristina Ramos Almeida, Claudio Ricci, Rogemar A. Riffel, Marko Stalevski

First listed 2026-09-25 | Last updated 2026-09-24

Abstract

Integral field spectroscopy (IFS) of the central kiloparsecs of active galactic nuclei (AGN) reveals a mixture of spatially coincident emission from star-formation and AGN feedback exciting the interstellar medium. Disentangling these components remains a challenge, as most spectral tracers are affected by both processes, limiting robust interpretation of kinematics and energetics. We present a new framework for decomposing IFS data into distinct components on a spaxel-by-spaxel basis using a multi-tracer, stacked kinematics approach. This method combines kinematic modelling with imposed flux decomposition per spaxel, quantifying the contribution of each component across the field of view. We apply this method to JWST IFS observations of the Seyfert galaxy NGC 5728 from the Galaxy Activity, Torus, and Outflow Survey (GATOS), analysing twelve mid-infrared fine-structure lines (4.49 < $λ$ < 25.89 $μ$m, 7.9 < IP < 126.2 eV). We find that the circumnuclear emission can be decomposed into two dominant components: a star-forming ring and an AGN-driven biconical outflow. Our method separates these structures and recovers their detailed spatial morphology. This framework provides a general and scalable method for physically motivated component separation in IFS data, applicable across many wavelength ranges and targets, enabling reliable interpretation of complex emission line structures (or morphologies) in active galaxies and beyond.

Short digest

Veenema et al. introduce a spaxel-by-spaxel IFS decomposition framework that stacks kinematic information from multiple emission lines, then imposes those component kinematics to apportion flux between physically distinct structures. Applied to combined JWST/NIRSpec and MIRI/MRS data for the Compton-thick Seyfert 2 NGC 5728, the method uses twelve mid-infrared fine-structure lines spanning ionisation potentials of 7.9–126.2 eV to separate its circumnuclear star-forming ring from the AGN-driven biconical outflow. The resulting maps recover the detailed morphology of both components even where low-ionisation tracers blend ring and outflow emission, while high-ionisation [Ne V] is confined to the AGN/outflow. This provides a scalable route to interpreting blended line structures and deriving component-resolved IFS measurements across facilities and wavelength ranges.

Key figures to inspect

• Figure 1. This side-by-side comparison establishes the observational problem the method solves: low-ionisation [Ne II] contains both the circumnuclear ring and outflow signatures, whereas high-ionisation [Ne V] isolates the AGN and biconical outflow. The flux and velocity maps make the contrasting spatial and kinematic tracers immediately visible.
• Figure 2. This is the conclusion-driving product of the stacked multi-line decomposition: the outflow flux-fraction map assigns each spaxel to AGN-driven outflow or star-forming disc dominance. It shows that the framework converts blended emission-line data into a physically interpretable, component-resolved view of the central region.