Can plasma physics establish a significant bound on long-range dark matter interactions?

Dark matter has been theorized to be charged under its own “dark electromagnetism” (dark-EM). Under this hypothesis, dark matter can behave like a cold collisionless plasma of self-interacting dark matter particles and exhibit plasmalike instabilities with observational consequences. Using the results published in [], which studied the degree of slowdown between two interpenetrating <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mi>e</a:mi><a:mo>−</a:mo></a:msup><a:msup><a:mi>e</a:mi><a:mo>+</a:mo></a:msup></a:math> plasma clouds due to plasma instabilities, estimates of similar interactions for colliding “dark plasmas” are explored. Comparison with astronomical observations reveals strong new constraints on dark-EM with the dark electromagnetic self-interaction <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msub><c:mi>α</c:mi><c:mi>D</c:mi></c:msub><c:mo>&lt;</c:mo><c:mn>4</c:mn><c:mo>×</c:mo><c:msup><c:mn>10</c:mn><c:mrow><c:mo>−</c:mo><c:mn>25</c:mn></c:mrow></c:msup></c:math>.