Speaker
Description
Observations with the James Webb Space Telescope have revealed a high abundance of bright z>10 galaxy candidates that challenge the predictions of standard theoretical models, particularly at the highest redshifts. Various explanations for this discrepancy have been proposed, such as feedback-free starbursts, radiation-driven outflows clearing the dust from star-forming regions, a top-heavy stellar initial mass function (IMF), or only detecting galaxies going through periods of intense star formation due to their faster growth in mass.
We have investigated whether an IMF that becomes increasingly top-heavy towards higher redshifts and lower gas metallicities or higher gas densities could explain these observations. We have built the first model that follows early galaxy evolution and reionisation while accounting for such evolving IMFs. Specifically, we have adjusted the descriptions for supernovae feedback, metal enrichment, and ionising and ultraviolet radiation emissions in the Astraeus framework that couples an N-body simulation with a semi-analytical model for galaxy evolution and a semi-numerical model for reionisation.
In this talk, I will show how our parameterisation of evolving IMFs changes the ultraviolet luminosity functions, the relations between different galactic properties (stellar mass, star formation rate, gas-phase metallicity, dust, ultraviolet luminosity) and the topology of the ionised regions growing around the galaxies in the intergalactic medium during reionisation compared to a constant Salpeter IMF.
