Although there is ample observational evidence for the existence of dark matter, we still lack a definitive characterization of its particle nature. The standard cosmological paradigm of collisionless cold dark matter ($Lambda$CDM) accurately predicts the physics of the Universe on large scales. However, at smaller scales, discrepancies emerge between observations and simulations. On galactic and sub-galactic scales (a few Mpc), observations appear to be at odds with the structure formation predicted by CDM numerical simulations, especially regarding dwarf galaxies and Milky-Way satellites.

These discrepancies also extend to more massive galaxies. The CDM model predicts a higher fraction of dark matter in the inner regions of galaxies than is observed. An alternative to CDM is required to explain this lower dark matter fraction in observations, and the Self-Interacting Dark Matter (SIDM) framework is a promising candidate. Within the SIDM framework, interactions between dark matter particles reshape the dwarf galaxies halo structure and reduce central dark matter densities.

Article in prep.