Addressing the self-interaction for ELDER dark matter from the 21-cm signal

The self-interacting dark matter can affect various cosmological processes. Such interactions can be number conserving (e.g. [Formula: see text]) or number violating (e.g. [Formula: see text]). The latter processes where three (or more) dark matter particles undergo self-annihilation/scattering to produce less number of dark matter is termed as Cannibalism process. In this work, the self-interaction of dark matter and the strength of such interactions are investigated in the light of experimental results of the global 21-cm spectrum of neutral hydrogen from the era of cosmic dawn. From the present work, it appears that [Formula: see text] process is much more dominant over the [Formula: see text] process. It is also found that such interactions affect the dark matter-baryon elastic scattering cross-section. The study also indicates the presence of multi-component dark matter of different mass ranges in the Universe.