Seminaire Lagrange -- Tommaso Ronconi (SISSA) -- Painting realistic radio skies: empirical recipes for the galaxy-halo connection to derive data-driven full-sky simulations for future radio surveys

Painting realistic radio skies: empirical recipes for the galaxy-halo connection to derive data-driven full-sky simulations for future radio surveys

The advent of new observational campaigns and upcoming radio surveys marks a transformative era in radio astrophysics and cosmology. As we anticipate the first light from the SKA Observatory, there is a critical need to prepare for the cosmological interpretation of wide field data. Mock datasets, which simulate expected observations, play a relevant role in this preparation. Empirical methods offer a valuable approach to investigate the galaxy-halo connection without imposing a priori assumptions on uncertain baryonic physics.

In this talk, I will discuss the methodologies we use to populate simulated hierarchies of dark matter haloes and sub-haloes with mock galaxies and demonstrate how the observable statistics in the generated catalogues mimic those observed from surveys. We combine different empirical recipes, including halo occupation distribution, sub-halo abundance matching or scattered sampling of empirical relations, in order to generate a realistic radio sky with populations of star forming galaxies, active galactic nuclei and 21cm line emitting neutral hydrogen galaxies.

I will show how this method, by independently coupling the three different populations of objects with the same simulated DM-only lightcone, is able to find counterparts without having to tune the models on any additional relation.

Being blind to ab initio physical assumptions, the class of models we use provides an unbiased method to investigate the dark sector properties that shape the observed sky. If time permits, I will conclude by discussing investigations on the use of reinforcement learning to enhance the galaxy assignment technique beyond the standard sub-halo-mass based models.