Four New Fast Radio Bursts Discovered in the Parkes 70-cm Pulsar Survey Archive

TL;DR

This paper reports the discovery of four new fast radio bursts in archival data, featuring unusually large widths and the highest known dispersion measure, highlighting the importance of reanalyzing pulsar survey archives for undetected FRBs.

Contribution

It introduces four new FRBs with large widths and high dispersion measures found in archival pulsar survey data, emphasizing the potential of such archives for FRB discovery.

Findings

Four new FRBs discovered with widths > 50 ms

One FRB has the largest DM (3338 pc cm$^{-3}$) to date

First FRBs detected by any radio telescope prior to the Lorimer Burst

Abstract

We present four new fast radio bursts discovered in a search of the Parkes 70-cm pulsar survey data archive for dispersed single pulses and bursts. We searched dispersion measures (DMs) ranging between 0 to 5000 pc cm$^{-3}$ with the HEIMDALL and FETCH detection and classification algorithms. All four of the FRBs discovered have significantly larger widths ($> 50$ ms) than almost all of the FRBs detected and cataloged to date. The large pulse widths are not dominated by interstellar scattering or dispersive smearing within channels. One of the FRBs has a DM of 3338 pc cm$^{3}$, the largest measured for any FRB to date. These are also the first FRBs detected by any radio telescope so far, predating the Lorimer Burst by almost a decade. Our results suggest that pulsar survey archives remain important sources of previously undetected FRBs and that searches for FRBs on time scales extending beyond $\sim 100$ ms may reveal the presence of a larger population of wide-pulse FRBs.