Ely D. Kovetz

Recent upper bounds from the Hydrogen Epoch of Reionization Array on the cosmological 21-cm power spectrum at redshifts z≈8, 10, have been used to constrain LX<2  keV/SFR, the soft-band x-ray luminosity measured per unit star formation rate (SFR), strongly disfavoring values lower than ≈1039.5  erg s−1 M⊙−1  yr. This conclusion is derived from seminumerical models of the 21-cm signal, specifically focusing on contributions from atomic cooling galaxies that host population II stars.

In this work we present 21cmfirstclass, a modified version of 21cmfast, the most popular code in the literature for computing the inhomogeneities of the 21-cm signal. Our code uses the public cosmic microwave background (CMB) Boltzmann code class, to establish consistent initial conditions at recombination for any set of cosmological parameters and evolves them throughout the dark ages, cosmic dawn, the epoch of heating and reionization.

In the preceding article, we introduce 21cmfirstclass, a new code for computing the 21-cm anisotropies, assembled from the merger of the two popular codes 21cmfast and class. Unlike the standard 21cmfast, which begins at z=35 with homogeneous temperature and ionization boxes, our code begins its calculations from recombination, evolves the signal through the dark ages, and naturally yields an inhomogeneous box at z=35.