Measuring the Coronal Magnetic Field with 2D Coronal Seismology: A Forward-Modeling Validation

TL;DR

This study validates a 2D coronal seismology technique using forward modeling, demonstrating it can accurately measure the magnetic field strength and direction in the solar corona from spectral-imaging data.

Contribution

The paper provides a validation of the 2D coronal seismology method through forward modeling, confirming its accuracy and robustness for measuring coronal magnetic fields.

Findings

The technique accurately recovers magnetic field strength and direction.

Close agreement between estimated and true magnetic fields in simulations.

Parameter analysis guides practical application of the method.

Abstract

In recent years, a two-dimensional (2D) coronal seismology technique applied to spectral-imaging data from the Coronal Multi-channel Polarimeter (CoMP) and UCoMP has enabled routine measurement of the global coronal magnetic field. The technique combines coronal transverse wave phase speed from Doppler measurements with electron densities from the Fe \sc{xiii}\rm{} 10798/10747 \AA\ intensity ratio to infer the magnetic field strength, while the wave propagation directions from Doppler measurements trace the magnetic field direction. To validate the accuracy and robustness of this method, we use forward modeling of a MURaM simulation that produces open and closed magnetic structures with excited waves. From the synthetic Doppler velocity, Fe \sc{xiii}\rm{} infrared line intensities, and linear polarization signals, we apply the 2D coronal seismology technique to estimate the magnetic field strength and direction. A comparison with the simulation ground truth shows close agreement, indicating that the technique can recover the line-of-sight emissivity-weighted magnetic field direction and strength with high accuracy. We also perform a parameter-space analysis to quantify sensitivities of the method to parameter choice. These findings provide practical guidance for CoMP/UCoMP-like analysis and demonstrate that 2D coronal seismology can deliver reliable, LOS emissivity-weighted measurements of the coronal magnetic field from coronal wave observations.