At https://phys.org/print446911328.html … Does dark matter carry an electric charge is the headline – which turns out to be a bit of PR. Astronomers, it is said, have produced a new model for the invisible matter that is supposed to make up most of the universe – the so called dark matter (unseen and unverified). These particular astronomers and modellers think dark matter might have an electric charge. However, this is just a 'tiny' electric charge – so they are not jumping in with both feet. Julian Munoz of Harvard says, 'the electric charge is on the very smallest of scales' – but it emerges they need an electric charge (which they don't like) solely to interact with ordinary matter (and its electro-magnetic properties).
Why the need to invoke an electric charge. Well, they have a problem. The recent EDGE team said there was a slump in the Cosmic Background Radiation around 200 million years after Big Bang – and this is a modeller's attempt to explain it (and invoking an electric current is one way to account for that slump). Dark matter is being targeted for the slump – but how does dark matter connect with ordinary matter (or the particles within it).