The three discrete nulling time-scales of PSR J1717−4054

• Published in: Monthly notices of the Royal Astronomical Society Vol. 445; no. 1; pp. 320 - 329
• Main Authors: Kerr, M., Hobbs, G., Shannon, R. M., Kiczynski, M., Hollow, R., Johnston, S.
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 21.11.2014
• Subjects: Arrays; Astronomy; Emission; Flux; Interstellar matter; Nulling; Position measurement; Pulsars; Radio telescopes; Space telescopes; Stars & galaxies; Australia; pulsars: individual: J1717−4054
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stu1716

PSR J1717−4054 is one of the small class of pulsars which null on intermediate (∼h) time-scales. Such pulsars represent an important link between classical nullers – whose emission vanishes for a few rotations – and the intermittent pulsars which null for months and years. Using the Parkes radio telescope and the Australia Telescope Compact Array, we have studied the emission from PSR J1717−4054 over intervals from single pulses to years. We have identified and characterized nulling at three discrete time-scales: the pulsar emits during ‘active states’ separated by nulls lasting many thousands of rotations, while active states themselves are interrupted by nulls with a bimodal distribution of durations – one to two rotations, or tens of rotations. We detect no sub-pulse structure or flux-density variations during active states, and we place stringent limits (<0.1 per cent of the mean active flux density) on pulsed emission during inactive states. Finally, our high-quality data have also allowed us to measure for the first time many important properties of PSR J1717−4054, including its position, spin-down rate, spectrum, polarization characteristics, and pulse broadening in the interstellar medium.