Quasi-regular variations of subpulse drifting for PSR J1857+0057

TL;DR

This study observes and analyzes quasi-regular subpulse drifting in PSR J1857+0057, revealing a 50-period modulation in drift rate and pulse intensity, with polarization data indicating subtle profile changes.

Contribution

It provides detailed measurements of drifting parameters and modulation patterns, highlighting the quasi-regular nature of subpulse drifting in this pulsar, which was not previously characterized.

Findings

Detection of 50-period low frequency modulation in drift rate and pulse intensity.

Inverse variation between drift periodicity P3 and pulse intensity.

Polarization data shows slight steepening of PA curve for certain drifting states.

Abstract

During observations of the Galactic Plane Pulsar Snapshot (GPPS) survey by the Five-hundred-meter Aperture Spherical radio Telescope (FAST), varying subpulses drifting of PSR J1857+0057 is detected. The following-up observation confirms the quasi-regularly changes of the drifting rate about every 50 periods. We determine the drift rate $D$ through a linear fit to the pulse-central longitudes of subpulses in a drifting band, and determine $P_3$ from the cross-points of two fitted lines at the zero longitude for two neighbored drifting bands. The low frequency modulation of about every 50 periods is found on variations of not only pulse intensity but also drift parameters. In most of low frequency modulation cycles, the integrated pulse intensity $I$ and the absolute drift rate $|D|$ tend to increase first and then decrease, and the drifting periodicity $P_3$ varies just in the opposite. In addition, the phase-forward intensity-enhancement is observed in many modulation cycles. Based on our polarization data, the average PA curve for pulses with a smaller $|D|$ and larger $P_3$ is slightly steep in the leading edge of pulse profile compared with that of the fully averaged profile.