The Grism Emission-line Kinematics tOol
GEKO
Written in JAX for optimal running speed on GPUs.
A novel state-of-the-art code to forward-model JWST grism data.
Visual representation of the RGB image of a galaxy and its associated NIRCam grism spectrum which is centered on the Ha emission line.
GEKO outputs for the modelling of a galaxy in the JADES survey.
How does it work?
GEKO combines a forward-modelling framework with Bayesian inference to recover the kinematics and morphologies of galaxies as traced by their nebular emission (e.g. Ha, [OIII], …). On the modelling side, GEKO creates a model 3D cube with the spatially resolved light profile of the emission line, and a velocity and velocity dispersion map encoded in the spectra of each pixel. The cube is then collapsed on the grism 2D plane after being convolved with the instrument PSF and LSF. Using this framework, GEKO is able to fit 2D grism emission line maps and infers the posterior distributions of the model parameters. The currently implemented models are a simple Sersic profile and an arctangeant velocity curve, but the flexible nature of the code allows for any models to be added.
