# Vacuum non-linear electrodynamic polarization effects in hard emission of pulsars and magnetars

## TL;DR

This paper explores how vacuum non-linear electrodynamics causes birefringence in pulsar emissions, predicting specific polarization effects that can be observed with high-precision measurements to test fundamental physics.

## Contribution

It provides a theoretical framework and observational strategy for detecting vacuum birefringence effects in pulsar emissions due to non-linear electrodynamics.

## Key findings

- The front part of pulsar pulses should be linearly polarized.
- The rest of the pulse can have arbitrary polarization.
- High-precision polarization measurements can reveal vacuum birefringence effects.

## Abstract

The non-linear electrodynamics influence of pulsar magnetic field on the electromagnetic pulse polarization is discussed from the point of observation interpretation. The calculations of pulsar magnetic field impact on electromagnetic pulse polarization are made in such a way to make it easier to interpret these effects in space experiments. The law of hard emission pulse propagation in the pulsar magnetic field according to the vacuum non-linear electrodynamics is obtained. It was shown, that due to the birefringence in the vacuum the front part of any hard emission pulse coming from a pulsar should be linearly polarized and the rest of pulse can have arbitrary polarization. Observational possibilities of vacuum birefringence are discussed. The estimations of detector parameters such as effective area, exposure time and necessity of polarization measurements with high accuracy are given. The combination of large area and extremely long exposure time gives the good opportunity to search the fine polarization effects like vacuum non-linear electrodynamics birefringence.