up to a factor of $\sim$few. Similarly, the fractional uncertainty on the average neutral fraction can be constrained to within $\lesssim10$ per cent for HERA and SKA1. By studying the resulting impact on astrophysical constraints, [<span style="font-variant:small-caps;">21CMMC</span>]{} can be used to optimize (i) interferometer designs; (ii) foreground cleaning algorithms; (iii) observing strategies; (iv) alternative statistics characterizing the 21 cm signal; and (v) synergies with other observational programs.'
author:
- |
    Bradley Greig$^{1}$[^1] & Andrei Mesinger$^{1}$\
    $^1$Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
bibliography:
- '21cmMC.bib'
title: '21CMMC: an MCMC analysis tool enabling astrophysical parameter studies of the cosmic 21 cm signal'
---

galaxies: high-redshift – intergalactic medium – cosmology: theory – dark ages, reionization, first stars – diffuse radiation – early Universe

Introduction
============

The epoch of reionization ([EoR]{}) describes the period of enlightenment following the cosmic dark ages, when density perturbations grow into the first astrophysical sources (stars and galaxies). These sources produce ultraviolet (UV) ionizing photons, which escape into the intergalactic medium ([IGM]{}) eventually reionizing the pervasive neutral hydrogen fog.

The [EoR]{} is rich in astrophysical information, probing the formation and evolution of structure in the Universe, the nature of the first stars and galaxies 