Mitigating Resampling Artifacts for the JWST Integral-field Unit Spectrometers with Adaptive Trace Modeling

The integral-field unit spectrometers on board the James Webb Space Telescope (JWST) undersample the nearly diffraction-limited point-spread function provided by the telescope optics. This undersampling produces large oscillating spectral artifacts when the data are resampled into regularly gridded data cubes, which poses a significant challenge for many scientific analyses. We describe here a generalized technique to use cubic basis spline models to interpolate the observed spectral traces onto a higher-resolution grid prior to data cube rectification, which largely eliminates these artifacts in addition to helping reduce biases in point-source spectra from clusters of bad pixels. We demonstrate the utility of this adaptive resampling technique for a variety of JWST/NIRSpec and MIRI/Medium Resolution Spectrometer observations ranging from isolated point sources to embedded active galactic nuclei, crowded stellar fields with diffuse emission, and protostars with rich molecular bands.