Constraining the Initial Mass Function in the Epoch of Reionization from Astrophysical and Cosmological Data

We aim to constrain the stellar initial mass function (IMF) during the epoch of reionization. To this purpose, we build up a semi-empirical model for the reionization history of the Universe based on various ingredients: the latest determination of the UV galaxy luminosity function from JWST out to redshift z≲12; data-inferred and simulation-driven assumptions on the redshift-dependent escape fraction of ionizing photons from primordial galaxies; a simple yet flexible parameterization of the IMF ϕ(m⋆)∼m⋆ξe−m⋆,c/m⋆ in terms of a high-mass end slope ξ