# Population modelling of FRBs from intrinsic properties

## TL;DR

This paper develops a Monte Carlo simulation method to infer intrinsic properties of FRBs from observational data, considering host galaxy contributions, plasma scattering, and spectral effects, providing insights into FRB populations and characteristics.

## Contribution

It introduces a novel simulation-based approach to estimate FRB source and host galaxy properties, accounting for scattering and spectral effects, which advances understanding of FRB origins and distributions.

## Key findings

- Intrinsic pulse broadening is very small, less than 1 ms.
- Host galaxy DM contribution is comparable to the Milky Way's.
- FRB energy decreases at higher frequencies with a negative spectral index.

## Abstract

We present a method to estimate the source properties of FRBs from observations by assuming a fixed DM contribution from a MW-like host galaxy, pulse temporal broadening models for turbulent plasma and a flat FRB energy spectrum. We then 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 $\lesssim 10^{-2}-1\ {\rm ms}$ from physical models, with the ISM contribution suppressed significantly relative to IGM. The intrinsic width for non-repeating FRBs is broadened by a factor $\sim 2-3$ on average primarily due to dispersive smearing. From the simulations, we find that the host galaxy DM 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 $\sim 2.0$ and then drops significantly at larger distances. We obtain the energy distribution for FRB 121102 with repetition rate $\sim 0.1-0.3\ {\rm hr^{-1}}$ 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 $\sim 0.8-0.9$ with the current follow-up data insufficient to suggest more than one class of FRB progenitors.