"The Goose" Pulsar Wind Nebula of PSR J1016-5857: The Birth of a Plerion

TL;DR

This study presents multi-wavelength observations of the pulsar PSR J1016-5857 and its PWN, revealing a tail-like morphology, proper motion, magnetic field orientation, spectral softening, and evidence of a relic PWN and SNR interaction.

Contribution

First detailed multi-wavelength analysis of PSR J1016-5857's PWN, including proper motion measurement and interpretation of PWN evolution and SNR interaction.

Findings

Pulsar proper motion estimated at 28.8 mas/yr with velocity ~440 km/s.

Radio polarization indicates magnetic field aligned with the pulsar tail.

Spectral softening suggests synchrotron burn-off and aging of the PWN.

Abstract

We report the results of X-ray (CXO) and radio (ATCA) observations of the pulsar wind nebula (PWN) powered by the young pulsar PSR J1016--5857, which we dub "the Goose" PWN. In both bands the images reveal a tail-like PWN morphology which can be attributed to pulsar's motion. By comparing archival and new CXO observations, we measure the pulsar's proper motion $\mu=28.8\pm7.3$ mas/yr, yielding a projected pulsar velocity $v \approx 440\pm110$ km/s (at d=3.2 kpc); its direction is consistent with the PWN shape. Radio emission from the PWN is polarized, with the magnetic field oriented along the pulsar tail. The radio tail connects to a larger radio structure (not seen in X-rays) which we interpret as a relic PWN (also known as a plerion). The spectral analysis of the CXO data shows that the PWN spectrum softens from $\Gamma=1.7$ to $\Gamma\approx2.3-2.5$ with increasing distance from the pulsar. The softening can be attributed to rapid synchrotron burn-off, which would explain the lack of X-ray emission from the older relic PWN. In addition to non-thermal PWN emission, we detected thermal emission from a hot plasma which we attribute to the host SNR. The radio PWN morphology and the proper motion of the pulsar suggest that the reverse shock passed through the pulsar's vicinity and pushed the PWN to one side.