VLT polarimetry observations of PSR B0656+14

TL;DR

This study reports the first optical polarisation measurement of pulsar PSR B0656+14 using VLT, finding a polarisation degree of about 12% and a potential alignment with its proper motion, suggesting magnetospheric insights.

Contribution

First measurement of phase-averaged optical polarisation for PSR B0656+14, exploring its alignment with proper motion to understand pulsar magnetosphere geometry.

Findings

Measured polarisation degree of 11.9%±5.5%.

Found polarisation angle close to proper motion direction.

Indicates possible magnetospheric alignment, requiring further confirmation.

Abstract

Optical polarisation measurements are key tests for different models of the pulsar magnetosphere. Furthermore, comparing the relative orientation of the phase-averaged linear polarisation direction and the pulsar proper motion vector may unveil a peculiar alignment, clearly seen in the Crab pulsar. Our goal is to obtain the first measurement of the phase-averaged optical linear polarisation of the fifth brightest optical pulsar, PSR\, B0656+14, which has also a precisely measured proper motion, and verify a possible alignment between the polarisation direction and the proper motion vector. We carried out observations with the Very Large Telescope (VLT) to measure the phase-averaged optical polarisation degree (P.D.) and position angle (P.A.) of PSR B0656+14. We measured a P.D. of $11.9\%\pm5.5\%$ and a P.A. of $125.8\degr\pm13.2\degr$, measured East of North. Albeit of marginal significance, this is the first measurement of the phase-averaged optical P. D. for this pulsar. Moreover, we found that the P.A. of the phase-averaged polarisation vector is close to that of the pulsar proper motion ($93.12\degr\pm0.38\degr$).Deeper observations are needed to confirm our polarisation measurement of \psr, whereas polarisation measurements for more pulsars will better assess possible correlations of the polarisation degree with the pulsar parameters.