Self-interacting dark matter without prejudice

Understand

The existence of dark matter particles that carry phenomenologically relevant self-interaction cross sections mediated by light dark sector states is considered to be severely constrained through a combination of experimental and observational data.

• The conclusion is based on the assumption of specific dark matter production mechanisms such as thermal freeze-out together with an extrapolation of a standard cosmological history beyond the epoch of primordial nucleosynthesis.
• In this work, we drop these assumptions and examine the scenario from the perspective of the current firm knowledge we have: results from direct and indirect dark matter searches and cosmological and astrophysical observations, without additional assumptions on dark matter genesis or the thermal state of the very early universe.
• We show that even in the minimal set-up, where dark matter particles self-interact via a kinetically mixed vector mediator, a significant amount of parameter space remains allowed.