Measurement of the electron density and magnetic field of the solar wind using millisecond pulsars

TL;DR

This paper demonstrates a method to simultaneously measure electron density and magnetic field in the solar wind near the Sun using millisecond pulsars, improving magnetic field estimation accuracy.

Contribution

It introduces a technique combining Faraday rotation and electron density measurements from millisecond pulsars to better estimate solar wind magnetic fields.

Findings

Simultaneous measurements enhance magnetic field estimation accuracy.

The method is effective at 6-10 solar radii.

Provides a new approach for solar wind magnetic field studies.

Abstract

The magnetic field of the solar wind near the Sun is very difficult to measure directly. Measurements of Faraday rotation of linearly polarized radio sources occulted by the solar wind provide a unique opportunity to estimate this magnetic field, and the technique has been widely used in the past. However Faraday rotation is a path integral of the product of electron density and the projection of the magnetic field on the path. The electron density near the Sun can be measured by several methods, but it is quite variable. Here we show that it is possible to measure the path integrated electron density and the Faraday rotation simultaneously at 6-10 $R_\odot$ using millisecond pulsars as the linearly polarized radio source. By analyzing the Faraday rotation measurements with and without the simultaneous electron density observations we show that these observations significantly improve the accuracy of the magnetic field estimates.