Detection of 49 Weak Dispersed Radio Pulses in a Parkes Observation of the X-ray Pulsar PSR J0537$-$6910

Abstract: I conducted a new search for dispersed radio pulses from the X-ray pulsar PSR J0537$-$6910 in the Large Magellanic Cloud in a long (11.6 hr) archival 1.4 GHz Parkes search observation. I searched dispersion measures (DMs) between 0 and 10000 pc cm$^{-3}$ and detected 49 pulses with a signal-to-noise ratio (S/N) greater than 7 at a wide range of DMs using the HEIMDALL and FETCH pulse detection and classification packages. All of the pulses were weak, with none having a S/N above 8.5. There was a significant excess of pulses observed in the DM range of the known pulsar population in the LMC, suggesting that these pulses may originate from LMC pulsars. Three repeat pulses, each having widths $\lesssim 1$ ms, were detected in a single DM trial of 103.412 pc cm$^{-3}$, which is in the LMC DM range. This is unlikely to occur by chance in a single DM trial in this search at the (marginally significant) 4.3$\sigma$ level. It remains unclear whether any of the detected pulses in the sample are from PSR J0537$-$6910 itself.