Decaying Dark Matter and the Hubble Tension

Understand

Decaying dark matter models generically modify the equation of state around the time of dark matter decay, and this in turn modifies the expansion rate of the Universe through the Friedmann equation.

• Thus, a priori, these models could solve or alleviate the Hubble tension, and depending on the lifetime of the dark matter, they can be classified as belonging to either the early- or late-time solutions.
• Moreover, decaying dark matter models can often be realized in particle physics models relatively easily.
• However, the implementations of these models in Einstein--Boltzmann solver codes are non-trivial, so not all incarnations have been tested.