Speaker
Description
We emphasize the distinctive cosmological dynamics in multi-component dark-matter scenarios and its impact in probing a sub-dominant component of dark matter.
The dynamics originates from the conversion among different dark-matter components.
We find that the temperature of the self-interacting sub-component dark matter is significantly enhanced by the dark-matter annihilation into the sub-component.
The same annihilation sharply increases the required annihilation cross section for the sub-component as we consider a smaller relative abundance fraction among the dark-matter species.
Because of the enhanced temperature and annihilation cross section of the sub-component, contrary to a naive expectation, it can be easier to detect the sub-component with smaller abundance fractions in dark-matter direct/indirect-detection experiments and cosmological observations.
Combining with the current results of accelerator-based experiments, the abundance fractions smaller than $10\,\%$ are strongly disfavored;
we demonstrate this by taking a dark photon portal scenario as an example.
Nevertheless, for the abundance fraction larger than $10\,\%$, the warm dark-matter constraints on the sub-dominant component at sub-${\rm GeV}$ mass scale can be complementary to the parameter space probed by accelerator-based experiments.
