We introduce a novel class of signatures---spectral edges and end points---in 21-cm measurements resulting from interactions between the standard dark sectors. Within context kinetically mixed photon, we demonstrate how resonant photon-to-photon conversions can imprint distinctive spectral features in observed brightness temperature, with implications for current, upcoming, proposed experiments...

Abstract We propose a two-component dark matter explanation to the EDGES 21 cm anomalous signal. The heavier component is long-lived, and its decay primarily responsible for relic abundance of lighter matter, which millicharged. To evade constraints from CMB, underground direct detection, XQC experiments, lifetime has be larger than , where age universe. Our model pro...