  The dark matter density distribution in small-scale astrophysical objects may
indicate that dark matter is self-interacting, while observations from clusters
of galaxies suggest that the corresponding cross section depends on the
velocity. Using a model-independent approach, we show that resonant
self-interacting dark matter (RSIDM) can naturally explain such a behavior. In
contrast to what is often assumed, this does not require a light mediator. We
present explicit realizations of this mechanism and discuss the corresponding
astrophysical constraints.
