A probe of the maximum energetics of fast radio bursts through a prolific repeating source

O. S. Ould-Boukattine, P. Chawla, J. W. T. Hessels, A. J. Cooper, M. P. Gawroński, W. Herrmann, F. Kirsten, D. M. Hewitt, D. C. Konijn, K. Nimmo, Z. Pleunis, W. Puchalska, M. P. Snelders

Published 2024-10-22Version 1

Fast radio bursts (FRBs) are sufficiently energetic to be detectable from luminosity distances up to at least seven billion parsecs (redshift $z > 1$). Probing the maximum energies and luminosities of FRBs constrains their emission mechanism and cosmological population. Here we investigate the maximum energetics of a highly active repeater, FRB 20220912A, using 1,500h of observations. We detect $130$ high-energy bursts and find a break in the burst energy distribution, with a flattening of the power-law slope at higher energy. This is consistent with the behaviour of another highly active repeater, FRB 20201124A. Furthermore, we model the rate of the highest-energy bursts and find a turnover at a characteristic spectral energy density of $E^{\textrm{char}}_{\nu} = 2.09^{+3.78}_{-1.04}\times10^{32}$ erg/Hz. This characteristic maximum energy agrees well with observations of apparently one-off FRBs, suggesting a common physical mechanism for their emission. The extreme burst energies push radiation and source models to their limit.