Evidence of vacuum birefringence from the polarisation of the optical emission from an Isolated Neutron Star

Abstract

Isolated Neutron Stars are some of the most exciting stellar objects known to astronomers: they have the most extreme magnetic fields, with values up to 10 15 G, and, with the exception of stellar-mass black holes, they are the most dense stars, with densities of ≈ 10 14 g cm −3 . As such, they are perfect laboratories to test theories of electromagnetism and nuclear physics under conditions of magnetic field and density unattainable on Earth. In particular, the interaction of radiation with strong magnetic fields is the cause of the vacuum birefringence, an effect predicted by quantum electrodynamics in 1936 but that lacked an observational evidence until now. Here, we show how the study of the polarisation of the optical radiation from the surface of an isolated neutron star yielded such an observational evidence, opening exciting perspectives for similar studies at other wavelengths.

Exploring the quantum vacuum via ultraintense laser-induced refraction of light

“…It is noted that certain astronomical systems, such as neutron stars, are surrounded by magnetic fields close to the Schwinger field. These extremely strong fields lead to significant effects related to vacuum polarization [27,28], such as vacuum birefringence [29][30][31], photon splitting [32], and etc [33,34]. More importantly, together with the advancement in modern optical detection system, many of these effects have the potential to be detected in experiments.…”