Magnetography of Solar Flaring Loops with Microwave Imaging Spectropolarimetry

TL;DR

This paper presents a framework for modeling microwave emissions from solar flaring loops to derive magnetic field maps, demonstrating promising results with realistic data and discussing future applications with advanced radio arrays.

Contribution

It introduces a comprehensive method for extracting 2D magnetic field maps from microwave spectropolarimetry data of solar flares, incorporating realistic geometries and instrumental effects.

Findings

High accuracy in parameter recovery from simulated data

Systematic effects due to resolution and line-of-sight variations

Potential for application with next-generation radio arrays

Abstract

We have developed a general framework for modeling gyrosynchrotron and free-free emission from solar flaring loops and used it to test the premise that 2D maps of source parameters, particularly magnetic field, can be deduced from spatially resolved microwave spectropolarimetry data. In this paper we show quantitative results for a flaring loop with a realistic magnetic geometry, derived from a magnetic field extrapolation, and containing an electron distribution with typical thermal and nonthermal parameters, after folding through the instrumental profile of a realistic interferometric array. We compare the parameters generated from forward fitting a homogeneous source model to each line of sight through the folded image data cube with both the original parameters used in the model and with parameters generated from forward fitting a homogeneous source model to the original (unfolded) image data cube. We find excellent agreement in general, but with systematic effects that can be understood as due to finite resolution in the folded images and the variation of parameters along the line of sight, which are ignored in the homogeneous source model. We discuss the use of such 2D parameter maps within a larger framework of 3D modeling, and the prospects for applying these methods to data from a new generation of multifrequency radio arrays now or soon to be available.