The impact of Lyman-Werner radiation on early galaxy formation

The launch of the James-Webb Space Telescope has opened a unique window into an era when the Universe was less than a billion years old.

This proposal aims at conducting physics-rich high-resolution simulation campaign of that epoch, that bridges the the formation of the first stars in small dark matter haloes all the way to massive dark matter haloes in which the first galaxies form.

The particular novel feature of these simulations is the inclusion of the most accurate background of UV photons (so-called Lyman-Werner photons). The latter are able to dissociate molecular Hydrogen and also hinder its formation. The consequence of this is the inability of primordial gas to cool down and to gravitationally collapse and form stars.

Typical state-of-the art simulations neglect Lyman-Werner radiation and thus have uncertainties in their predicted star formation rates.

We will present strong constraints on the star formation rate and build up of stellar mass in galaxies based on our simulations.

In addition to these predictions we will investigate the onset of reionization in the Universe, a phase during which neutral Hydrogen atoms got ionized by photons. The main sources for Lyman-Werner radiation are stars in the Universe.

The masses and luminosities of the first generation of stars are still uncertain at this point and we will investigate the impact of different mass choices on the resulting Lyman-Werner background.