A rare non-drifting state in the subpulse drifting pulsar J1059-5742

Abstract

We report single-pulse observation of PSR J1059-5742 carried out with the 64-m Parkes radio telescope. Single-pulse analysis of the observation identifies three distinct emission states: a dominant subpulse-drifting state, a rare brighter non-drifting state, and short nulls. Our study show that 96.2% of the pulsar’s radio radiation is in the drifting state. In the drifting state, subpulses drift toward earlier longitudes, with drift periods of \(P_{3} = 5.7\pm 0.5 P\) and \(P_{2} = 5.6\pm 0.7^{\circ }\). In the observation, we detect two rare non-drifting state events. The two non-drifting-state events persist for 107 and 108 rotation periods respectively. These two events accounted for 3.8% of the total observing time. Compared with single pulses in the drifting state, those in the non-drifting state are brighter, and the peak of the average pulse profile for the non-drifting state leads that of the drifting state by about \(2^{\circ }\) in spin longitude. This implies that changes may have occurred in the polar-cap discharge process or the magnetospheric configuration. Examination of the energies of all detected single-pulses revealed that the pulsar may have a nulling fraction of \(13\pm 1\%\), and pulse nulling occurs only within the drifting state. The occasional cessation of drifting in PSR J1059-5742 may thus reveal a mode change of the polar-cap discharge.