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

Abstract

PSR J1717-4054 is one of the small class of pulsars which null on\nintermediate (~hour) timescales. Such pulsars represent an important link\nbetween classical nullers, whose emission vanishes for a few rotations, and the\nintermittent pulsars which null for months and years. Using the Parkes radio\ntelescope and the Australia Telescope Compact Array, we have studied the\nemission from PSR J1717-4054 over intervals from single pulses to years. We\nhave identified and characterised nulling at three discrete timescales: the\npulsar emits during "active states" separated by nulls lasting many thousands\nof rotations, while active states themselves are interrupted by nulls with a\nbimodal distribution of durations; one to two rotations, or tens of rotations.\nWe detect no subpulse structure or flux density variations during active\nstates, and we place stringent limits (<0.1% of the mean active flux density)\non pulsed emission during inactive states. Finally, our high-quality data have\nalso allowed us to measure for the first time many important properties of PSR\nJ1717-4054, including its position, spindown rate, spectrum, polarization\ncharacteristics, and pulse broadening in the interstellar medium.\n