Cosmological birefringent constraints on light

TL;DR

This paper investigates vacuum birefringence effects predicted by the Standard-Model Extension (SME) and uses cosmological spectropolarimetry data to set stringent bounds on Lorentz invariance violation coefficients, confirming isotropy of light speed.

Contribution

It provides the first calculation of sub-leading order birefringence effects in the CPT-even SME and derives new, tighter bounds on LIV coefficients from cosmological observations.

Findings

LIV coefficients are constrained to less than 10^{-16}.

Improves previous bounds on parity-odd coefficients by two orders of magnitude.

Confirms isotropy of the one-way light speed with high precision.

Abstract

We calculate the birefringent in the vacuum for light at the leading and sub-leading orders for the CPT-even part of the SME. We report that all the LIV coefficients absent in the leading order, but the isotropic one, contributes to the sub-leading order birefringent. We consider models free of the first order birefringent. We then show that infrared, optical, and ultraviolet spectropolarimetry of cosmological sources bound the LIV coefficients to less than $ 10^{-16}$. This improves the best current bound on the parity-odd coefficients by two orders of magnitude and establishes the isotropy of the one-way light speed with the precision of $41 \frac{nm}{s}$.