Abstract
Radiative corrections of quantum electrodynamics cause a vacuum threaded by a magnetic field to be birefringent. This means that radiation of different polarizations travels at different speeds. Even in the strong magnetic fields of astrophysical sources, the difference in speed is small. However, it has profound consequences for the extent of polarization expected from strongly magnetized sources. We demonstrate how the birefringence arises from first principles, show how birefringence affects the polarization state of radiation and present recent calculations for the expected polarization from magnetars and X-ray pulsars.
Highlights
The second prediction of quantum electrodynamics (QED) was the birefringence of the vacuum [1,2], in particular that light travels through a magnetic field at different speeds depending on its polarization
To demonstrate the importance of QED vacuum birefringence on the X-ray polarization from neutron stars, we focus on two particular objects: the magnetar 4U 0142+61 and the X-ray pulsar
We have presented an ab initio derivation of the effective Lagrangian of quantum electrodynamics and the induced vacuum birefringence
Summary
The second prediction of quantum electrodynamics (QED) was the birefringence of the vacuum [1,2], in particular that light travels through a magnetic field at different speeds depending on its polarization. This came only eight years after the formulation of relativistic quantum mechanics [3]. Even in the magnetic fields of the most strongly magnetized objects in the Universe, the magnetars, the difference in the index of refraction is only a few percent; the vacuum birefringence can increase the observed extent of polarization in the X-rays by a factor of ten even for more weakly magnetized objects
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
