Challenges to the Two-Infall Scenario

Welcome to the repository for Dubay et al. (2026), "Challenges to the Two-Infall Scenario by Large Stellar Age Catalogs" (accepted for publication in The Astrophysical Journal). Read the paper at arXiv:2508.00988.

To re-build the article yourself, first ensure you have the right packages by creating a Conda environment from the environment.yml file:

$ conda env create -f environment.yml
$ conda activate twoinfall

Next, download and extract the model outputs from the Zenodo archive at 10.5281/zenodo.16649938. Place the extracted multizone directory within the src/data folder.

Alternatively, all 11 multi-zone models can be run from scratch:

$ ulimit -n 30000
$ bash run_all_models.sh

Please allow approximately 6 hours for all the models to run. Note: This will replace everything in the src/data/multizone directory, including the output files from Zenodo.

To re-create all the plots and tables in the paper, run the following:

$ bash all_paper_plots.sh

Repository Structure

.
├── src
│   ├── data                # Catalog files and model outputs (ignored by git)
│   ├── extra               # Non-paper figures and other outputs (ignored by git)
│   ├── scripts             # Python scripts for figures and models
│   ├── ├── multizone       # Source code for multi-zone chemical evolution models
│   ├── tex                 # LaTeX files
│   ├── ├── figures         # Programatically-generated figures
│   ├── ├── output          # Programatically-generated tables and other outputs
├── all_paper_plots.sh      # Script to produce all paper figures
├── run_all_models.sh       # Script to run all multi-zone models
├── environment.yml         # Package dependencies
├── LICENSE
└── README.md

Note that some scripts, such as multizone_plots.py, generate additional figures for multi-zone model outputs that not included in the manuscript. The output of these scripts is saved in src/extra.

Source code for the models is located within the multizone directory. To run a single multi-zone model with custom parameters, run the following:

$ cd src/scripts
$ python -m multizone [OPTIONS...]

Software Dependencies

This code is built on the Versatile Integrator for Chemical Evolution (VICE) package (Johnson & Weinberg 2020). VICE is necessary for the code to run, and should be installed automatically using environment.yml.

We also include a copy of the Chemical Evolution Analysis Package (ChEAP) developed by Palicio et al. (2023). This is included at src/scripts/CheapTools.py for convenience, so it does not need to be installed separately.