Constraining the Fast Radio Burst (FRB) properties using the detections at Parkes, ASKAP and CHIME

We demonstrate how the FRB redshift and fluence distributions from the Parkes, ASKAP and CHIME telescopes can be used together to constrain the properties of the FRB population. Here we consider a simple model where all the FRBs have the same spectral index $\alpha$ and rest frame energy $E$ (specified in a fixed band $2128\;{\rm MHz}$ to $2848\;{\rm MHz}$). We find that the constraints on $(\alpha,E)$ depend on the scattering model for pulse broadening in the inter-galactic medium. For no scattering we find that there is a region of parameter space where the predictions are simultaneously consistent with the FRB redshift and fluence distributions at all three telescopes. The allowed $\alpha$ range is bounded by $-6.0\leq \alpha \leq-3.6$ and the allowed $E$ range is bounded by $1.79\times 10^{33}{\rm J} \leq E \leq 5.41\times 10^{33}{\rm J}$. Our analysis also rules out an empirical scattering model where the FRB pulse broadening in the IGM is predicted by extrapolating pulse broadening observed for pulsars in the ISM.