2020ApJ...899..124B

We present a method to estimate the source properties of Fast Radio Bursts (FRBs) from observations by assuming a fixed dispersion measure contribution from a Milky Way-like host galaxy, pulse temporal broadening models for turbulent plasma, and a flat FRB energy spectrum. Then we perform Monte Carlo simulations to constrain the properties of the FRB source, its host galaxy, and scattering in the intervening plasma from the observational data of FRBs detected with Parkes. The typical scatter broadening of the intrinsic pulse is found to be considerably small, <= 10^–2 - 1 ms, from physical models, with the interstellar medium contribution suppressed significantly relative to that of the intergalactic medium. The intrinsic width for nonrepeating FRBs is broadened by a factor of ∼2-3 on average, primarily due to dispersive smearing. From the simulations, we find that the host galaxy dispersion measure contribution is likely to be comparable to the Galactic contribution and the FRB energy decreases significantly at high frequencies with a negative spectral index. The FRB spatial density is found to increase up to redshift ∼2.0 and then drops significantly at larger distances. We obtain the energy distribution for FRB 121102 with repetition rate ∼0.1-0.3 hr^–1 and exponential energy cutoff that is significantly smaller compared to typical FRB energies. We find that the probability of observing none of the other FRBs to be repeating at Parkes is ∼0.8-0.9 with the current follow-up data insufficient to suggest more than one class of FRB progenitors.