Charged Dark Matter and the $H_0$ tension
Abstract
We consider cosmological models where dark matter is charged under a dark Abelian gauge field. This new interaction is repulsive and competes with gravity on large scales and in the dynamics of galaxies and clusters. We focus on nonlinear models of dark electrodynamics where the effects of the new force are screened within a Kmouflage radius that helps avoiding traditional constraints on charged dark matter models. We discuss the background cosmology of these models in a Newtonian approach and show the equivalence with relativistic Lemaître models where an inhomogeneous pressure due to the electrostatic interaction is present. In particular, we find that dark matter shells of different radii evolve differently as they exit their Kmouflage radii at different times, resulting in a breaking of the initial comoving evolution. In the large time regime, the background cosmology is described by comoving but inhomogeneous model with a reduced gravitational Newton constant and a negative curvature originating from the electrostatic pressure. Baryons do not directly feel the electrostatic interaction, but are influenced by the inhomogeneous matter distribution induced by the electric force. We find that shells of smaller radii evolve faster than the outer shells which feel the repulsive interaction earlier. This mimics the discrepancy between the large scale Hubble rate and the local one. Similarly, as galaxies and clusters are not screened by the new interaction, large scale global flows would result from the existence of the new dark electromagnetic interaction.
 Publication:

arXiv eprints
 Pub Date:
 April 2020
 arXiv:
 arXiv:2004.13677
 Bibcode:
 2020arXiv200413677B
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology
 EPrint:
 27 pages, 18 figures, added references, updated figures, improved discussion, conclusions unchanged. Accepted in PRD