Polarization of the charge-exchange X-rays induced in the Heliosphere

TL;DR

This study theoretically investigates the polarization of X-ray emissions caused by charge-exchange collisions between solar wind ions and hydrogen atoms in the Heliosphere, predicting polarization levels between 3% and 8%.

Contribution

It provides the first detailed theoretical predictions of X-ray polarization in the Heliosphere considering various solar wind conditions and line-of-sight geometries.

Findings

Polarization varies from 3% to 8% depending on conditions.

Polarization depends on solar wind velocity and observation geometry.

Results aid in interpreting heliospheric X-ray observations.

Abstract

We report results of a theoretical investigation of polarization of the X-ray emissions induced in charge-exchange collisions of fully stripped solar wind ions C$^{6+}$ and O$^{8+}$ with the heliospheric hydrogen atoms. The polarization of X-ray emissions has been computed for line-of-sight observations within the ecliptic plane as a function of solar wind ion velocities, including a range of velocities corresponding to the slow and fast solar wind, and Coronal Mass Ejections. To determine the variability of polarization of heliospheric X-ray emissions, the polarization has been computed for solar minimum conditions with self-consistent parameters of the solar wind plasma and heliospheric gas and compared with the polarization calculated for an averaged solar activity. We predict the polarization of charge-exchange X-rays to be between 3% and 8%, depending on the line-of-sight geometry, solar wind ion velocity, and the selected emission lines.