On the detectability of extragalactic fast radio transients

Understand

Recent discoveries of highly dispersed millisecond radio bursts by Thornton et al.

• in a survey with the Parkes radio telescope at 1.4 GHz point towards an emerging population of sources at cosmological distances whose origin is currently unclear.
• Here we demonstrate that the scattering effects at lower radio frequencies are less than previously thought, and that the bursts could be detectable at redshifts out to about $z=0.5$ in surveys below 1 GHz.
• Using a source model in which the bursts are standard candles with bolometric luminosities $\sim 8 \times 10^{44}$ ergs/s uniformly distributed per unit comoving volume, we derive an expression for the observed peak flux density as a function of redshift and use this, together with the rate estimates found by Thornton et al.