Inferring the Distances of Fast Radio Bursts Through 21-cm Absorption

Ben Margalit, Abraham Loeb

Published 2015-11-11Version 1

The distances of Fast Radio Burst (FRB) sources are currently unknown. We show that the 21-cm absorption line of hydrogen can be used to infer the redshifts of FRB sources, and determine whether they are Galactic or extragalactic. We calculate a probability of $\sim 10\%$ for detecting a 21-cm equivalent width $\gtrsim 4 ~\mathrm{km}~\mathrm{s}^{-1}$. The forthcoming SKA observatory provides ideal prospects for detecting our predicted signal.