Warm Surprises from Cold Duets: Cosmological Implications of Two-Component Dark Matter
Heong Han Kim
Chungbuk National University, Korea
The cosmological data from a small-scale astrophysical structure and future gravitational wave (GW) experiments hold great promise in shedding light on the nature of dark matter (DM). First, we explore a two-component DM model with a sizable mass splitting and self-interaction for a light component. By delving into temperature evolution, density perturbation, and N-body simulation, we find that the annihilation of the heavier components to the lighter ones effectively endows the latter with warm DM-like behavior. It takes advantage of all the distinct features that warm DM offers without observational mass constraints on the warm DM masses. Second, we explore a black hole binary system in the presence of the ultralight self-interacting scalar DM and corresponding GW signals. The dense region of DM can lead to the dephasing of gravitational waveforms, which can be detected by upcoming experiments such as LISA.
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