Key points are not available for this paper at this time.
The observation of an absorption feature in the 21-cm spectrum at redshift z≈17 implies bounds on dark-matter (DM) annihilations for a broad range of masses, given that significant heating of the intergalactic medium would have erased such a feature. The resulting bounds on the DM annihilation cross sections are comparable to the strongest ones from all other observables.
D’Amico et al. (Mon,) studied this question.