Cue is a flexible tool for interpreting nebular emission across a wide range of ionizing conditions of galaxies. It is a neural net emulator based on the Cloudy photoionization code. Cue does not require a specific ionizing spectrum as a source, instead approximating the ionizing spectrum with a 4-part piece-wise power-law. Along with the flexible ionizing spectra, Cue allows freedom in [O/H], [N/O], [C/O], gas density, and total ionizing photon budget.
git clone https://github.com/yi-jia-li/cue.git
cd cue
python -m pip install .
pip uninstall astro-cue
An example of making the nebular line and continuum prediction based on the cue parameters:
from cue.line import predict as line_predict
from cue.continuum import predict as cont_predict
par = [[21.5, 14.85, 6.45, 3.15, 4.55, 0.7, 0.85, 49.58, 10**2.5, -0.85, -0.134, -0.134]]
lines = line_predict(theta=par).nn_predict()
cont = cont_predict(theta=par).nn_predict()
An example of fitting emission lines with cue in demo/cue_demo.ipynb
A list of the emulated lines can be found in data/lineList.dat
If you use this code, please reference this paper:
@ARTICLE{2025ApJ...986....9L,
author = {{Li}, Yijia and {Leja}, Joel and {Johnson}, Benjamin D. and {Tacchella}, Sandro and {Davies}, Rebecca and {Belli}, Sirio and {Park}, Minjung and {Emami}, Razieh},
title = "{Cue: A Fast and Flexible Photoionization Emulator for Modeling Nebular Emission Powered by Almost Any Ionizing Source}",
journal = {\apj},
keywords = {Photoionization, H II regions, Interstellar medium, Stellar populations, Active galactic nuclei, Galaxy evolution, 2060, 694, 847, 1622, 16, 594, Astrophysics - Astrophysics of Galaxies},
year = 2025,
month = jun,
volume = {986},
number = {1},
eid = {9},
pages = {9},
doi = {10.3847/1538-4357/adcab4},
archivePrefix = {arXiv},
eprint = {2405.04598},
primaryClass = {astro-ph.GA},
adsurl = {https://ui.adsabs.harvard.edu/abs/2025ApJ...986....9L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}