Gamma-ray polarization constraints on Planck scale violations of special relativity

TL;DR

This paper uses X-ray polarization data from the Crab Nebula to set stringent limits on Planck-scale Lorentz violations, significantly improving previous constraints and highlighting future observational prospects.

Contribution

It provides the tightest constraints to date on Lorentz violation parameters using astrophysical polarization measurements.

Findings

Constraints on Lorentz violation parameter |\xi| < 9x10^{-10} at 3 sigma

Future X-ray polarimeters could probe |\xi| ~ 10^{-16}

Vacuum birefringence effects are strongly constrained by observations

Abstract

Using recent polarimetric observations of the Crab Nebula in the hard X-ray band by INTEGRAL, we show that the absence of vacuum birefringence effects constrains O(E/M) Lorentz violation in QED to the level |\xi| < 9x10^{-10} at three sigma CL, tightening by more than three orders of magnitude previous constraints. We show that planned X-ray polarimeters have the potential the potential to probe |\xi|~ 10^{-16} by detecting polarization in active galaxies at red-shift ~1.