Bounds on Dark Matter decay from 21 cm line
  The observation of the cosmic 21-cm spectrum can serve as a probe for Dark
Matter properties. We point out that the knowledge of the signal amplitude at a
given redshift allows one to put conservative bounds on the DM decay rate which
are independent of astrophysical parameters. These limits are valid for the
vast majority of DM models, those without extra IGM cooling or additional
background radiation. Using the experimental results reported by the EDGES
collaboration, we derive bounds that are stronger than the ones derived from
other CMB observations and competitive with the ones from indirect detection.
