Interstellar Scintillation and the Radio Counterpart of the Fast Radio Burst FRB150418

Understand

Keane et al.

• (2016) have recently reported the discovery of a new fast radio burst, FRB150418, with a promising radio counterpart at 5.5 and 7.5 GHz -- a rapidly decaying source, falling from 200-300 $\mu$Jy to 100 $\mu$Jy on timescales of $\sim$6 d.
• This transient source may be associated with an elliptical galaxy at redshift $z=0.492$, providing the first firm spectroscopic redshift for a FRB and the ability to estimate the density of baryons in the intergalactic medium via the combination of known redshift and radio dispersion of the FRB.
• An alternative explanation, first suggested by Williams & Berger (2016b), is that the identified counterpart may instead be a compact AGN.