Lorentz violation induced vacuum birefringence and its astrophysical consequences
arXiv:1104.4438 · doi:10.1103/PhysRevD.83.127702
Abstract
In the electromagnetism of loop quantum gravity, two helicities of a photon have different phase velocities and group velocities, termed as "vacuum birefringence". Two novel phenomenons, "peak doubling" and "de-polarization", are expected to appear for a linearly polarized light from astrophysical sources. We show that the criteria to observe these two phenomenons are the same. Further, from recently observed -ray polarization from Cygnus X-1, we obtain an upper limit for Lorentz-violating parameter , which is the most firm constraint from well-known systems. We also suggest to analyze possible existence of "peak doubling" through Fermi LAT GRBs.
4 latex pages, 2 figures, short version for publication in PRD. For a detailed long version, please look at the first version of this arXiv paperarXiv:1104.4438v1