Challenges to the CDM model and the AIDA-TNG simulations

One of the foundations of the concordance cosmological model is that approximately 85 per cent of the matter content of the Universe is in the form of some yet unknown component that we can detect only through its gravitational effect: dark matter. While the standard Cold Dark Matter model is very successful at explaining the large-scale-structure distribution of the universe, it has been challenged by observations at the scale of galaxies and below. Recently, the lensing properties of subhaloes appear inconsistent with CDM: the observed lensing signal is inferred to be stronger than predicted, and the subhalo concentrations required to explain it are outliers within the CDM model. I will review these recent results, the observational analyses and the simulations used in the comparison and discuss possible solutions to this tension, including alternative dark matter scenarios as self-interacting dark matter. In light of these issues, I will also present the first results from the new AIDA-TNG sample, where we simulated two cosmological volumes with CDM, WDM and SIDM models together with galaxy formation. Such simulations will be crucial to understand the effect of alternative dark matter models on multiple scales and observables.