Zeus21: Lightning-fast simulations of cosmic dawn

Zeus21 encodes the effective model for the 21-cm power spectrum and global signal from Muñoz 2023a. The goal is to capture all the nonlocal and nonlinear physics of cosmic dawn in a light and fully Pythonic code. Zeus21 takes advantage of the approximate log-normality of the star-formation rate density (SFRD) during cosmic dawn to compute the 21-cm power spectrum analytically. It agrees with more expensive semi-numerical simulations to roughly 10% precision, but has comparably negligible computational cost (~ s) and memory requirements. Now Zeus21 can also predict galaxy UV luminosity functions (UVLFs) and their linear clustering (galaxy bias) at any z, see Muñoz et al. 2023b for the implementation and application to JWST. Now Zeus21 includes Population III stars with inhomogeneous Lyman-Werner feedback and relative velocities (with their fluctuations), as described in Cruz et al. 2024.

Zeus21 (Zippy Early-Universe Solver for 21-cm) pairs well with data from HERA, but can be used for any 21-cm inference or prediction. Current capabilities include finding the 21-cm power spectrum (at a broad range of k and z), the global signal, IGM temperatures (Tk, Ts, Tcolor), neutral fraction xHI, Lyman-alpha fluxes, and the evolution of the SFRD; all across cosmic dawn z=5-35. Zeus21 can use three different astrophysical models, one of which emulates 21cmFAST, and can vary the cosmology through CLASS.

If you want to get started I recommend checking the Jupyter tutorials in docs/. Full documentation in ReadTheDocs, more coming soon. Here is an example power spectrum (at k=0.3/Mpc) and global signal as a function of redshift, for two cases of X-ray luminosity. You can run it yourself with the tutorial included!

Currently you can find tutorials for:

• Basics, running and plotting 21-cm power spectra and global signals.
• UVLFs, comparing to HST and JWST predictions at high redshifts.
• PopIII stars, and how they affect the cosmic-dawn 21-cm signal.

Installation

You can download and install this package by doing:

git clone https://github.com/julianbmunoz/zeus21.git zeus21 cd zeus21/ pip install .

that should take care of all dependencies (remember to work in your favorite conda env). If you have issues with cache'd versions of packages you can add --no-cache-dir at the end of pip install ..

NOTE: You may run into problems when pip-installing classy (the Python wrapper of CLASS). If so, their installation guide is here, but in short the steps are:

git clone https://github.com/lesgourg/class_public.git class cd class/ make cd python/ python setup.py install --user

(modifying the Makefile to your gcc as needed)

Citation

If you find this code useful please cite:

An Effective Model for the Cosmic-Dawn 21-cm Signal

and include a link to this Github.

If you use the UVLF module please cite:

Breaking degeneracies in the first galaxies with clustering

And if you use relative velocites, Lyman-Werner feedback, or Population III stars please cite:

The First Billion Years in Seconds: An Effective Model for the 21-cm Signal with Population III Stars.