Open AccessThe high‐energy polarization‐limiting radius of neutron star magnetospheres – I. Slowly rotating neutron stars
Author(s) -
Heyl Jeremy S.,
Shaviv Nir J.,
Lloyd Don
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2003.06521.x
Subject(s) - physics , neutron star , polarization (electrochemistry) , pulsar , polarization in astronomy , astrophysics , magnetic field , photon , magnetosphere , birefringence , linear polarization , optics , laser , chemistry , quantum mechanics
In the presence of strong magnetic fields, the vacuum becomes a birefringent medium. We show that this quantum electrodynamics effect decouples the polarization modes of photons leaving the neutron star (NS) surface. Both the total intensity and the intensity in each of the two modes are preserved along the path of a ray through the NS magnetosphere. We analyse the consequences that this effect has on aligning the observed polarization vectors across the image of the stellar surface to generate large net polarizations. In contrast to previous predictions, we show that the thermal radiation of NSs should be highly polarized even in the optical. When detected, this polarization will be the first demonstration of vacuum birefringence. It could be used as a tool to prove the high magnetic field nature of anomalous X‐ray pulsars (AXPs) and it could also be used to constrain physical NS parameters, such as R / M , to which the net polarization is sensitive.