# Prospects for Detecting X-ray Polarization in Blazar Jets

## TL;DR

This paper predicts X-ray polarization levels in blazar jets using existing data and models, identifying promising candidates for future polarization detection missions like IXPE.

## Contribution

It introduces a method to estimate X-ray polarization in blazars based on lower energy data and variability, highlighting new potential targets for polarization observations.

## Key findings

- High-peak blazars like Mrk 421 are easily measurable in 100 ks exposures.
- Most low-peak sources require bright flares for detection.
- Some intermediate-peak sources may have unexpectedly high polarization levels.

## Abstract

X-ray polarization should provide new probes of magnetic field geometry and acceleration physics near the base of blazar jets, but near-future missions will have limited sensitivity. We thus use existing lower energy data and X-ray variability measurements in the context of a basic synchro-Compton model to predict the X-ray polarization level and the probability of detection success for individual sources, listing the most attractive candidates for an IXPE campaign. We find that, as expected, several high-peak blazars such as Mrk 421 can be easily measured in 100 ksec exposures. Most low peak sources should only be accessible to triggered campaigns during bright flares. Surprisingly, a few intermediate peak sources can have anomalously high X-ray polarization and thus are attractive targets.