Screening away the $H_0$ tension

This Essay explores consequences of a dark non-linear electromagnetic sector in a Universe with a net dark charge for matter. The cosmological dynamics can be described by a Lema\^itre model and understood thanks to a screening mechanism driven by the electromagnetic non-linearities that suppress the dark force on small scales. Only at low redshift, when the screening scale enters the Hubble horizon, do cosmological structures commence to feel the dark repulsion. This repulsive force enhances the local value of the Hubble constant, thus providing a promising scenario for solving the Hubble tension. Remarkably, the dark electromagnetic interaction can have a crucial impact on peculiar velocities, i.e. introducing a bias in their reconstruction methods, and having the potential to explain the presence of a dark flow.