In a recent Letter in Physical Review D, selected for the Physics newsmagazine of the American Physical Society and as Editor’s Suggestion, a team of researchers of GoLP (Nitin S, now at CINECA, Kevin S, now in Bochum U, and Luis OS), established a new strong bound on dark electromagnetism, the equivalent of electromagnetism to dark mattter. Dark matter and its properties are at the core of some of the most fundamental questions in physics and the present work shows that plasma physics inspired models and simulations can help constrain some of the properties of dark matter.

The simplest model for an electromagnetic-like interaction in the dark sector is equivalent to the electromagnetic interaction between opposite dark charge identical mass particles i.e. dark electromagnetism. Under this hypothesis, dark matter can behave like a cold collisionless plasma of self-interacting dark matter particles, and exhibit plasma-like instabilities with observational consequences.The collisions of dark pair plasma clouds could then be unstable to collisionless plasma-like streaming instabilities. Using results from the slowdown measured in large scale numerical simulations, and comparisons with astronomical observations of the Bullet cluster, the paper establishes almost gravity-like constrains to the simplest model of dark electromagnetism, thus significantly limiting the range of physical parameters (mass and interaction strength) that could be present in the dark sector.