"Quantized Inertia further predicts that for objects with very low accelerations, such as stars at the edges of galaxies, the Rindler horizon moves so far back that it is close to the cosmic horizon so the waves of Unruh radiation are now damped equally all around, and the mechanism of inertia collapses. This explains why stars at the edge of galaxies can orbit faster than expected but still remain bound to the galaxy. As a result, Quantised Inertia predicts galaxy rotation perfectly without the need for dark matter or any adjustment (McCulloch, 2012, 2017)."

Source: https://quantizedinertia.com/about/