VLT polarimetry observations of the middle-aged pulsar PSR B0656+14

Moran, Paul
Shearer, Andrew
Mignani, RP,Moran, P,Shearer, A,Testa, V,Slowikowska, A,Rudak, B,Krzeszowki, K,Kanbach, G (2015) 'VLT polarimetry observations of the middle-aged pulsar PSR B0656+14'. Astronomy & Astrophysics, 583 .
Context. 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.Aims. 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 also has a precisely measured proper motion, and to verify a possible alignment between the polarisation direction and the proper motion vector.Methods. We carried out observations with the Very Large Telescope (VLT) to measure the phase-averaged optical polarisation degree (PD) and position angle (PA) of PSR B0656+14.Results. We measured a PD of 11.9% +/- 5.5% and a PA of 125.8 degrees +/- 13.2 degrees, measured east of north. Albeit of marginal significance, this is the first measurement of the phase-averaged optical PD for this pulsar. Moreover, we found that the PA of the phase-averaged polarisation vector is close to that of the pulsar proper motion (93.12 degrees +/- 0.38 degrees).Conclusions. Deeper observations are needed to confirm our polarisation measurement of PSR B0656+14, whereas polarisation measurements for more pulsars will better assess possible correlations of the polarisation degree with the pulsar parameters.
EDP Sciences
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