Single-pulse behaviours and fast radio burst-like micropulses in FAST wide-band observations of eight pulsars

We searched for evidence of subpulse drifting and micropulses from eight pulsars. Our observations were carried out using the ultra-wide-bandwidth receiver installed on the Five-hundred-meter Aperture Spherical radio Telescope (FAST), as part of the pilot program for the Commensal Radio Astronomy FAST Survey (CRAFTS). For three pulsars (PSRs J0426+4933, J0815+4611, J1529+40), we detected single pulses for the first time. Four pulsars [PSRs J0426+4933, J0815+4611, J1529+40, J1945-0040 (B1942-00)] were observed to undergo subpulse drifting. Notable features include bimodal behaviour in the nulling of PSR J0034-0721 (B0031-07). For this pulsar, short-duration (less than or similar to 10 period) null events were shown to be frequency-dependent, whereas long-duration null events were frequency-independent. The driftings of the pulse components for this pulsar overlapped in time, and the integrated profiles of the drift modes are shown to be distinct, indicating a different energy distribution. Subpulse drifting is detected for PSR J0426+4933 at similar to 400 MHz, but becomes undetectable above 600 MHz, probably becuase of the disappearance of one pulse component. Microstructures have been detected in pulses from PSRs J0034-0721 and J0151-0635 (B0148-06). The quasi-periodic microstructure emission in PSR J0034-0721 was detectable at low observing frequencies. The duration of the micropulses was found to be frequency-dependent. In a similar fashion to fast radio bursts, the detected micropulses were bandwith-limited, with a characteristic bandwidth of 128.4 +/- 31.6 MHz for PSR J0034-0721 and of 93.3 +/- 3.2 MHz for PSR J0151-0635.

Automated summary

We observed evidence of subpulse drifting and micropulses in eight pulsars using the ultra-wide-bandwidth receiver on FAST. Three pulsars showed single pulses for the first time, and four pulsars exhibited subpulse drifting. PSR J0034-0721 displayed bimodal behavior in nulling, with short-duration null events being frequency-dependent and long-duration null events being frequency-independent. We also detected microstructures in the pulses of PSR J0034-0721 and PSR J0151-0635.