SHIRO: Spectral Homogenization, Infrared Radial Output

SHIRO is a JWST/MIRI MRS analysis pipeline for spatially resolved studies of polycyclic aromatic hydrocarbon (PAH) emission in galaxies.

Developed and tested using observations of NGC 7469, the pipeline provides an end-to-end workflow for extracting annular spectra, stitching MIRI spectral channels, performing PAHFIT decomposition, propagating uncertainties through Monte Carlo simulations, and analyzing PAH populations using PAHdb.

Pipeline Overview

The notebook performs the following steps:

1. Discovery and loading of MIRI/MRS spectral cubes
2. Spatial homogenization through PSF matching
3. Quality-assurance maps with annular overlays
4. Annular spectral extraction
5. Pre-stitch spectral diagnostics
6. Spectral stitching across sub-bands and channels
7. Spectral decomposition with PAHFIT
8. Extraction of PAH-only spectra
9. Monte Carlo uncertainty estimation
10. PAH band-ratio measurements with propagated uncertainties
11. Radial trend analysis
12. PAH population analysis using PAHdb

Repository Contents

• SHIRO - Spectral Homogenization, Infrared Radial Output.ipynb

  Complete end-to-end analysis pipeline.

Using the Pipeline for Other Galaxies

To adapt the workflow to a new target:

• Set galaxy_folder to the directory containing the JWST/MIRI _s3d.fits cubes.
• Update REDSHIFT to the target galaxy value.
• Adjust the annular extraction parameters (num_rings, r0, and step) as needed.
• Verify that the PAHFIT feature names in BAND_COMPLEXES match those produced by PAHFIT for the target.

External Data Requirements

This repository does not distribute JWST data products or PAHdb databases.

JWST Data

Users must provide their own JWST/MIRI MRS _s3d.fits cubes.

PAHdb

PAHdb files must be downloaded separately and placed in a local PAHdb/ directory.

The databases are not distributed through this repository because of their size.

Scientific Improvements Relative to Earlier Versions

• Consistent redshift handling throughout the workflow
• Science-ready PSF homogenization
• Monte Carlo uncertainty propagation
• PAH band-ratio uncertainties included in final plots
• Improved robustness in PAHFIT feature extraction

Citation

If you use SHIRO in academic work, please cite the repository using the metadata provided in CITATION.cff.

GitHub will automatically generate citation formats through the repository's Cite this repository feature.

Acknowledgments

Developed at the Observatório do Valongo, Universidade Federal do Rio de Janeiro (UFRJ).

Advisor: Karín Menéndez-Delmestre

Author: Juan José Maldonado-Portilla

License

MIT License. See LICENSE for details.