21cmSPACE

21cmSPACE is a closed source, actively developed, semi-numerical code written (mostly) in MATLAB that models the 21-cm signal and other high-redshift observables from before the Cosmic Dawn (z~50) to the end of Epoch of Reionization (z~6). It is a versatile tool that can be used to study the 21-cm signal affected by a wide range of astrophysical processes, including the formation and properties of the first stars and galaxies, the impact of X-ray binaries, exotic scenarios of excess radio background, and more! Due to its semi-numerical nature, each simulation takes a few hours to run, making it ideal for parameter space exploration.

Development publications

A number of papers have been published on the development of 21cmSPACE over the years. Here is a list of them:

• Fialkov et al. (2012) — Impact of baryon-dark matter streaming velocity (vbc), semi-analytic prescription.

• Visbal et al. (2012) — 3D simulations of the 21-cm signal from Cosmic Dawn (X-ray heating and vbc).

• Fialkov et al. (2013) — Impact of Lyman-Werner feedback w/o vbc

• Fialkov et al. (2014a) — Inhomogeneous Lyman-alpha coupling (the WF effect)

• Fialkov et al. (2014b) — Realistic X-ray SED from high-mass X-ray binaries 

• Fialkov et al. (2014c) — Implementation of the excursion set formalism for reionization. Comparison between the signatures of soft and hard X-ray SEDs

• Cohen et al. (2016) — Photo-heating feedback

• Fialkov et al. (2017) — Miniquasars vs X-ray binaries (soft/hard SEDs). First unresolved X-ray background constraints

• Cohen et al. (2017) — 21-cm parameter space exploration using global signal 

• Cohen et al. (2018) —21-cm parameter space exploration using power spectra

• Fialkov & Barkana (2019) — Uniform excess radio background and CMB heating, astrophysical interpretation of EDGES Low-Band  detection

• Reis et al. (2020) — Inhomogeneous radio background from galaxies, astrophysical interpretation of EDGES Low-Band  detection

• Reis et al. (2021) — Lyman-alpha multiple scattering, Ly-a heating

• Reis et al. (2022) — Poisson fluctuations in star-forming halos

• Magg et al. (2022) — PopIII star formation and PopIII to PopII transition

• Gessey-Jones et al. (2022) — PopIII stars and IMF variation, including Lyman band effects only: WF effect, LW feedback, Ly-a heating.

• Gessey-Jones et al. (2023) — Cosmic ray heating model

• Sikder et al. (2024) — Line of sight radio effect

• Dhandha et al. (2025) — UVLF observable and flexible PopII SFE model

• Liu et al. (2025) - PopIII CHE stars, including ionization effets

Apart from the above, the code has been used in a number of other publications, using it for inference, forecasting, and more which are listed below.  

Inference with 21cmSPACE

A number of papers have been published on data interpretation, inference and parameter estimation using 21cmSPACE:

• Singh et al. (2017) — First results from SARAS2

• Singh et al. (2018) — Reanalysis of SARAS2 data

• Monsalve et al. (2019) — Analysis of EDGES High-Band

• Cohen et al. (2020) — First global signal emulator (21cmGEM) created using the first large set of 21-cm models (~30,000 signals produced on Harvard's Odyssey cluster). 

• Mondal et al. (2020) — LOFAR constraints with an excess radio background

• Bevins et al. (2021) — GLOBALEMU 

• Abdurashidova et al. (2022) — HERA collaboration: Early constraints from HERA using radio background models

• Bye et al. (2022) — 21cmVAE - emulator based on variational autoencoder 

• Bevins et al. (2022a) —a Bayesian reanalysis of SARAS 2 data 

• Bevins et al. (2022b) —astrophysical constraints from SARAS 3 non-detections

• Abdurashidova et al. (2023) — HERA collaboration: improved constraints from HERA

TBC...

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